Timeline of the Half-Life and Portal universe

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"Time, Doctor Freeman? Is it really that time again?"

― The G-Man

The known timeline of the Half-Life and Portal universe spans mostly from Earth's 20th century to its far future. This timespan sees the rise and fall of rival scientific research corporations Aperture Science and Black Mesa, the Combine's invasion and occupation of Earth in the aftermath of the Black Mesa Incident, and the uprising of humanity against them.

The following timeline has been constructed by gathering established dates and the events that have transpired in the series. Several retcons have been made since the first Half-Life game released in 1998, so more recent developments may contradict older material. Additionally, the events of Half-Life: Alyx indicate the storyline does not always occur linearly as events in both the series' past and future can be further manipulated.

On issuing precise dates on an official timeline, Marc Laidlaw, then-lead writer at Valve, stated the company doubted they ever would because of the possibility of contradicting themselves in the future. As the original Half-Life takes place in the deliberately vague year of "200-", leaving the years from 2000 to 2009 being open to possibility, some of the following dates are provided as time ranges due to being relative to the events of the first game. Some in-universe happenings are based on real-world information and as such may not reflect series canon; these are denoted with the Valve logo ().

"Eons" before 202-

• The Combine invades the homeworld of the Nihilanth, Vortigaunts, and Alien Grunts, prompting the homeworld's denizens to migrate to Xen. The Nihilanth takes over the borderworld and enslaves the Vortigaunts.

• 

  Depiction of the Combine's invasion.

• 

  Depiction of the Vortigaunts' enslavement.

18th Century

1770s

Between 1773 and 1782

• The Terminal publishes its first issue.

19th Century

1860s

1860

• Chatka Vodka is established in St. Petersburg, Russia.

• 

1870s

Between 1874 and 1883

• The Times publishes its first issue.

1890s

1891

• Year engraved on metal railings found throughout City 17 and St. Olga. (Non-canonical appearance)
• Chesterfield European style lager is established.

• 
• 

1892

• Bashkir beer is established in Sterlitamak, Russia.

• 

20th Century

1900s

1901

• Delicious fish sardines in tomato sauce is established.

• 

1902

• The UP Pioneer Press publishes its first issue.

1930s

Between 1936 and 1937

• One version of Cave Johnson is born.

1938

• An advertisement for various bitters is painted.

• 

1940s

1943

• By now, Cave Johnson has founded Aperture Fixtures, primarily manufacturing shower curtains for the US military, with Johnson receiving Aperture's Shower Curtain Salesman award.

• 

1944

• On January 6, Cave Johnson appears in The UP Pioneer Press headlines for buying a salt mine in Upper Michigan.

• 

Between 1944 and 1954

• Richard Keller is born.

• 

  Keller, aged 55.

1947

• Aperture Science Innovators is established, receiving the Science and Business Institute of America's Best New Science Company award.

• 
• 

Between 1947 and 1957

• Wallace Breen is born.

• 

  Portrait of Breen from The Terminal, aged 52.

1949

• Aperture Science is rated #2 among the Top 100 Applied Science Companies by Mechanical Engineering World Journal.

• 

1950s

• During this decade, Black Mesa Research Facility is built on top of several decommissioned ICBM launch and testing silo complexes.

• 

  Photo of Black Mesa, New Mexico.

• 

  Portrait of Cave Johnson during this decade.

1952

• Aperture Science builds Test Shaft 09's Entrance Way, Lobby and Testing Lounge, and Pump Station Alpha no earlier than this year.
• Aperture is the US Department of Defense's Contractor of the Year runner up.
• Around now, Aperture inadvertently creates "an army of Mantis Men".

• 
• 

  Pump Station Alpha exterior.

• 
• 

  Mantis Man bobblehead. (Non-canonical appearance)

1953

• Aperture Science's secondary R&D efforts focus on primitive portal technology and Repulsion Gel, building Test Shaft 09's Enrichment Sphere 01's Test Chamber 01, and begins building Chamber 02.

• 
• 

  Repulsion Gel in situ.

• 
• 

1954

• Aperture Science is the US Department of Defense's Contractor of the Year runner up again.

• 

1955

• Aperture Science receives the Spirit of Idaho National Potato Board award for the promotion of Potato Science.

• 

1956

• The Eisenhower administration awards Aperture Science a contract to provide shower curtains to all branches of the US military except the Navy, while leading astronauts, war heroes, and Olympians are invited to Aperture to help with the testing of ground-breaking inventions.
• By now, Pump Station Alpha is active, with Aperture finishing building Test Shaft 09's Enrichment Sphere 01's Test Chamber 02.

• 
• 

1957

• Aperture Science builds Test Shaft 09's Enrichment Sphere 02's Test Chamber 02.
• From now to 1973, Aperture produces mostly shower curtains.
• Kurdzhips semi-sweet red wine is established.

• 
• 

1958

• By now, Aperture Science's Repulsion Gel, being marketed as a dietetic pudding substitute, is pulled from shelves "for various reasons"; Aperture revamps and continues experimentation on it as a testing element.
• Aperture begins forming control groups for experimentation with cranial microchip implantation.
• Aperture builds Test Shaft 09's Enrichment Sphere 03's Test Chambers 27 and 28, and around now begins testing on time travel.

• 
• 
• 
• 

1960s

1961

• On June 15, Aperture Science's Test Shaft 09 "Zulu Bunsen" is condemned, abandoned and sealed off.

• 
• 
• 

  Test Shaft 09 abandonment hatch.

1968

• Aperture Science becomes a vital participant in the US Senate hearings on missing astronauts.

Between 1968 and 1978

• Colette Green is born.

• 

  Green, aged 31.

1970s

• During this decade, Grady and an unnamed Aperture Science employee inadvertently invent "toilet turrets". (Non-canonical appearance)

• 

  Aperture logo during this decade.

• 

  Portrait of Cave Johnson during this decade.

• 

  Ditto, with assistant Caroline.

• 

  Grady presenting a Mk. I toilet turret. (Non-canonical appearance)

1971

• Around now, Aperture has gone bankrupt.
• Aperture Science re-opens Test Shaft 09, building Pump Station Beta and a new entrance way, and an underground drydock no earlier than this year.

• 
• 
• 

  Underground drydock.

1972

• Aperture Science builds Test Shaft 09's Enrichment Sphere 04's Test Chambers 01 and 02.

• 
• 

Between 1972 and 1982

• Gordon Freeman is born.

• 

  Gordon, aged 27.

1973

• "Aperture Laboratories GLaDOS" is copyrighted by Aperture for the use of a bulletin board system.
• Aperture no longer produces mostly shower curtains.

1974

• Cave Johnson secretly develops a dangerous mercury-injected rubber sheeting, from which he plans to manufacture seven deadly shower curtains to be given as gifts to each member of the House Naval Appropriations committee.

Between 1974 and 1984

• Gina Cross is born.

• 

  Cross, aged 25.

1975

• Lane Electronics manufactures a circuit connector.

• 

1976

• Aperture Science builds Test Shaft 09's Enrichment Sphere 05's Test Chamber 05.
• By October 17, Cave Johnson realizes that testing on prominent members of society can be problematic, especially if they go missing; he profiles what he deems as "low risk" test subjects, the profile released internally in a confidential memo to select Aperture employees.

• 
• 

Between 1977 and 1987

• Adrian Shephard is born.

• 

  Shephard, aged 22.

1978

• Aperture Science begins using homeless people as test subjects, the object of testing and experimentation being Propulsion Gel. Complementing this, Aperture begins experimenting with human deconstruction, enhancement, and reconstruction procedures.
• Aperture builds an entrance way to the Main Lift via the Propulsion Gel test track of Test Shaft 09.

• 

  Egregious depiction of a homeless Aperture test subject.

• 

  Propulsion Gel in situ.

• 

Between 1978 and 1988

• At age six, Gordon Freeman constructs a butane-powered tennis ball cannon.

1979

• Cave Johnson acquires $70 million worth of moon rocks for their superior portal conductor properties. In experimenting with the lunar material, he grinds it up and mixes it into a new gel he calls Conversion Gel. Unfortunately, Johnson soon discovers that ground up moon rocks are highly poisonous and he begins to become deathly ill.

• 

  Moon rock.

1980s

• 

  Aperture (dba Aperture Laboratories) logo used from this decade onward.

• 

  Portrait of Cave Johnson during this decade.

1980

• Both of Cave Johnson’s kidneys fail. Brain damaged, dying, and incapable of being convinced that time is not now flowing backwards, Johnson lays out a three-tier R&D program:

1. The Heimlich Counter-Maneuver.

2. The Take-A-Wish Foundation.

3. Improved portal technology that he cryptically refers to as “Some kind of rip in the fabric of space…”

1981

• Diligent Aperture Science engineers complete the Heimlich Counter-Maneuver and Take-A-Wish Foundation initiatives. The company announces products related to the research in a lavish, televised ceremony. These products immediately become wildly unpopular. After a very public string of choking and despondent sick child disasters, senior company officials are summoned before a Senate investigative committee. During these proceedings, an engineer mentions that significant progress has been made on "Tier 3", the “man-sized ad hoc quantum tunnel through physical space with possible applications as a shower curtain.” The committee is quickly and permanently recessed, and Aperture is granted an open-ended contract to secretly continue research on portal technology and the "Heimlich Counter-Maneuver" project.
• Aperture builds a new Test Subject Waiting Area, around now using its own employees as test subjects, replacing any lost with robot workers.

• 
• 
• 
• 
• 
• 

1982

• Increasingly ill, Cave Johnson pushes forward with the new Conversion Gel. Due to his illness, Johnson also becomes interested in artificial intelligence and brain mapping. His hopes are that a successful brain map would allow a person's intelligence and consciousness to be implanted into a computer. In particular, he sees this as a possible way to overcome his poisoning and defeat death. Johnson states that if he dies before work is complete, his assistant Caroline is to succeed him as CEO of Aperture Science and have her consciousness put into a computer, even against her will.
• Earliest known use of the Enrichment Center Test Subject Application Process being applied to Aperture's test subjects. It is operated by version 1.07 of GLaDOS, later updated to versions 1.07a and 1.09.
• Aperture builds Test Shaft 09's Pump Station Gamma, Enrichment Sphere 06's test chamber and an entrance way to the Main Lift from Enrichment Sphere 07.
• Two images of cakes celebrating this year, one on October 29, are among several images in GLaDOS' databanks.

• 

  Conversion Gel in situ.

• 
• 
• 
• 
• 
• 

1983

• From now to 1985, work progresses on Aperture Science's “Portal” project. Several high ranking Fatah personnel choke to death on lamb chunks despite the intervention of their bodyguards.
• Aperture publishes a "Girls of Aperture Science" calendar.
• Images of cakes celebrating October 1 and November 19, respectively, are among several images in GLaDOS' databanks.

• 

  Calendar defaced with picture of a Companion Cube.

• 
• 

1984

• Images of cakes celebrating August 11 and September 15, respectively, are among several images in GLaDOS' databanks.

• 
• 

1985

• Earliest known use of the Aperture Image Format.
• An image of a cake celebrating September 27 is among several images in GLaDOS' databanks.

• 

1986

• Word reaches Aperture Science management that competing rival defense contractor Black Mesa is working on similar portal technology. In response to this news, Aperture begins developing GLaDOS to be used as an artificially intelligent research assistant (or "genetic lifeform") and disk operating system.
• Test Shaft 09's Enrichment Sphere 06's test chamber is fitted with a new wall.
• Duke animal feed is established.
• A toy rocket signed "Paul P." is dated this year.
• An image of a cake celebrating February 8 is among several images in GLaDOS' databanks.

• 

  Black Mesa logo in GLaDOS' databanks.

• 
• 
• 
• 

Late 1980s

• Cave Johnson dies from moon rock poisoning. Caroline succeeds him as CEO of Aperture Science.

1987

• Latest known use of the Aperture Image Format.

1988

• A number of versions of Aperture Laboratories across the multiverse near bankruptcy and each establish their own Extra-Earth Outsourcing and Perpetual Testing Initiative.

• 

1989

• A prototype chassis for GLaDOS is built, but subsequently abandoned.
• Aperture Science, dba The Lab, begins testing on pocket universes. (Non-canonical appearance)

• 

  GLaDOS' original prototype chassis.

• 

1990s

1991

• Rkaciteli white wine is established.

• 

Between 1991 and 200-

• Following the end of the Cold War, Black Mesa acquires the White Forest bunker in response to budgetary and oversight problems.

• 

  White Forest's south entrance

1994

• On January 21, 25, and 28, several Aperture Laboratories employees sign a blueprint of the Borealis.

• 

Between 1995 and 2005

• Alyx Vance is born.

• 

  Photo of infant Alyx, with parents Azian and Eli.

1996

• After a decade spent bringing the Disk Operating System parts of GLaDOS to a state of basic functionality, Aperture Science begins work on the Genetic Lifeform component. To implement the Genetic Lifeform component, the essence of Caroline is infused into the existing OS to provide the basis for GLaDOS' thought process.

1997

• Latest known use of a bulletin board system by Aperture Laboratories. By now, GLaDOS is version 3.11.
• While visiting the University of Innsbruck, Gordon Freeman observes a series of seminal teleportation experiments conducted by the Institute for Experimental Physics. Practical applications for teleportation become his obsession.

• 

1998

• Aperture Laboratories releases several testing elements, and a "Remember Your Evacuation Training" service announcement.
• From January 5 to August 16, an exhibit on "Ink on Paper — Young Masters" from 1870-1930 is held at the National Art Gallery of the Eastern European city that would later become City 17. The Gallery is open weekdays, Sundays, and holidays, 10 a.m. to 5 p.m.
• In December, the "extreme" tarragon-flavored Grunge soda is labeled "Flavor of the Month".

• 
• 
• 
• 
• 
• 
• 
• 
• 
• 

1999

• Gordon Freeman receives his doctorate from M.I.T. with a thesis paper entitled Observation of Einstein-Podolsky-Rosen Entanglement on Superquantum Structures by Induction through Nonlinear Transuranic Crystal of Extremely Long Wavelength (ELW) Pulse from Mode-Locked Source Array.
• A woman named Sarah takes a photo of her cat Beatrice.
• From September 25 to March 12, 2000, an exhibit on "Tyrannosaurus rex - The ultimate predator" is held at the newly renovated Prehistoric Hall of the Museum of Natural History of the Eastern European city that would later become City 17. The museum is open Tuesday - Saturday, 10 a.m. - 6 p.m., and Sunday, 11 a.m. - 4 p.m.
• On November 1, the US War Department issues its Soldier's Field Manual handbook.

• 

  Gordon's doctorate, top-left.

• 
• 
• 

Between 1999 and 2008

• Chell makes a potato battery for her class project.

2000

• On January 13, the US War Department issues an updated copy of its Basic Field Manual soldier's handbook.

21st Century

2000s

2001

• On December 5, the keycard of Terminal Authority employee Fyodor Todorova was set to expire. The card is ultimately never invalidated after this date, as Alyx Vance ends up using it over a decade later.

• 

2002

• On September 28, the keycard of Terminal Authority employee Zdravka Damyanovska was set to expire. The card is ultimately never invalidated after this date, as Alyx Vance ends up using it over a decade later.

• 

2006

• An image of a cake celebrating July 4 is among several images in GLaDOS' databanks.

• 

200-

• Russell applies for a job at the Black Mesa Research Facility. His application is rejected, and he is told to reapply the following year; this never occurs because of the Black Mesa Incident.

March

• Cpl. Adrian Shephard pens several entries in his diary:

• "March 3rd: Another typically hellish day at base camp... I'll be glad when this is over and I can get assigned a mission. There has been this really weird civie spotted at the base. Rumor is he's from some government branch looking to recruit; others say he's with some secret research group. I would jump at the chance to join. It would be cool just for the change and the adventure."
• "March 7th: I finally saw the government guy today. I'm not sure he is a g-man, but he was wearing a really uptight suit and carrying a briefcase. He looked more like a lawyer or insurance agent to me. I did notice him checking me out. Several times throughout the day I spotted him just watching me during training. I wonder what he's up to..."
• "March 9th: For weeks our drills have been the same crap day after day. Today we assemble for the morning run and our drill instructor tells us we have one week to become experts at indoor strategic combat. We will be spending every day this week at the combat simulation facility. As far as I know this a specialized training not taught in boot camp. What I want to know is if this is to test our ability to adapt or if we are being readied for a specific mission? Time will tell..."
• "March 12th: The rumors have been flying since our indoor combat training began. Most of my peers are convinced that we are being primed for a mission. No one can agree on what the mission is. I have heard the name Black Mesa Facility thrown around a lot, but I have no information about the place. The rumors are that some top-secret research is going on there. Doesn't sound too exciting to me..."
• "March 15th: The rumor has been confirmed. We are being trained for a mission at the Black Mesa Facility. All I know is that the place is being used by scientists who are doing some kind of new research. I can't imagine what we would be needed for. We were told today to be ready in case it happens tomorrow. I don't know what "it" is, but the whole thing is a little strange. I kind of hope it doesn't happen; the mission doesn't seem to have much excitement potential. I'd rather hold out for something with more likelihood of combat."

• 
• 

  Santego Military Base.

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  "G-man" observing Shephard.

• 
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  Senior Drill Instructor Dwight T. Barnes.

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  A few of Shephard's peers of the Hazardous Environment Combat Unit.

• 

"Mere weeks" before the Seven Hour War

• The global market is "soaring", with investors "riding high".

May 5

• While concluding his affairs at the University of Innsbruck, Dr. Gordon Freeman is sent a letter from the Black Mesa Office of the Administrator's L.M. confirming his acceptance for a position at the Research Facility, effectively immediately. Dr. Judith Mossman, who was up for the same job as Gordon, is edged out with his Innsbruck experience and Dr. Isaac Kleiner's personal recommendation.

• 
• 
• 

  Mossman, 202-.

• 

  Picture of Kleiner from Popular Scientist.

"A week" before May 16

• Suspected period an ichthyosaur was claimed to have been "hauled" from the Challenger Deep to Black Mesa.

• 

  Ichthyosaur.

"Days" before May 16

• Around now, Aperture Science's research icebreaker the Borealis and part of its drydock disappear during testing and development. The events surrounding the Borealis become highly classified.
• The untested GLaDOS AI is activated for the first time as one of the planned activities on Aperture's first annual Bring Your Daughter to Work Day. In many ways, the initial test goes well: Immediately, within one picosecond of being switched on, GLaDOS becomes self-aware. The "going well" phase lasts for two more picoseconds, at which point GLaDOS takes control of the facility and locks it down, trapping everyone inside. She then deploys a deadly neurotoxin which kills the majority of the scientists within the facility. A few survivors manage to install a Morality Core into GLaDOS which prohibits her from using the neurotoxin again. With the Morality Core in place, GLaDOS turns her attention back to the facility and begins testing. Her goal: beat the hated Black Mesa in the race to develop a functioning portal technology.

• 

  Borealis after its disappearance.

• 

  BYDTWD exhibition.

• 

  Chell's potato experiment for the BYDTWD science fair.

• 

  Depiction of GLaDOS' activation.

• 

  Morality Core attached to GLaDOS.

May 9

• Barney Calhoun is sent a letter from L.M. regarding his reassignment to the Black Mesa Security Force's Blue Shift effective May 15.

• 
• 

  Barney.

May 11

• Dr. Colette Green is sent a letter from L.M. informing her of Black Mesa senior staff's decision that sample GG-3883 will replace EP-0021.

• 
• 

  GG-3883.

May 12

• By now, Barney Calhoun is processed for a salary increase and retinal scan, and his two-day training course is scheduled.
• At 8:00 AM, Barney begins the first day of his two-day Security Guard training under security officer Miller's holographic assistant counterpart.

• 
• 

  Miller's hologram.

May 13

• Second day of Barney Calhoun's two-day training course.
• At 10:30 AM, Dr. Walter Bennet is being trained by Dr. Gina Cross for an Anti-Mass Spectrometer Overload Simulation.

• 
• 

  Bennet.

• 

  Anti-Mass Spectrometer.

May 14

• At 19:00 AM, Colette Green was to be trained by Isaac Kleiner on Anomalous Materials Handling, but this is rescheduled to June; this never occurs because of the Black Mesa Incident.

• 

May 15

• The latest date Gordon Freeman would take on his position at Black Mesa.
• At 9:00 AM, Barney Calhoun reports to the Sector C Area 3 Medium Security Facilities' section manager where he is provided his assignment. Barney is assigned to a 0900 - 2200 Blue Shift until August 15. Various other security officers are assigned to Red, Orange, Yellow, Green and Indigo Shifts throughout various areas and times in the facility, respectively, while Violet Shift is on standby.
• At 20:00 PM, Gina Cross is being trained by Dr. Richard Keller on an HEV Mk. 5 Prototype.

• 
• 

May 16

Morning

• At 7:30 AM, Gordon Freeman is being trained by Gina Cross' holographic counterpart on the Hazardous Environment Suit in the Black Mesa Training Facility. Prior to the training run, the scientists monitoring Gordon mention that the sensors in their equipment are not working, and "things are in a state of commotion".
• The experiment on sample GG-3883 in the anti-mass spectrometer was to be performed at 8:30 AM, but this is delayed by at least half an hour due to Gordon running late to work.
• Further system crashes and security malfunctions occur throughout Sector C at "about" 8:40 AM.
• At 8:42 AM, Barney Barney begins his tram ride from the Area 8 Topside Dormitories to start his second day of Blue Shift.
• At approximately 8:46 AM, Barney passes Gordon waiting on a Level 3 Dormitories tram platform.
• At 8:47 AM, Gordon begins his tram ride. He passes Barney banging on a door to the Sector C Area 3 Medium Security Facilities; topside temperature is 93° Fahrenheit.
• At approximately 9:00 AM, Barney gears up for his shift and receives orders to travel to Sector G to see what he can do about restoring power to its main access lift for two stuck scientists. Viewing a security feed, Barney witnesses Gordon arriving at the Anomalous Materials Laboratory "about half an hour" late, as well as Gina Cross preparing sample GG-3883 for the experiment.
• On his way to gearing up in his HEV suit, Gordon destroys Dr. Arne Magnusson's microwave casserole in the lab's cafeteria.

• 
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  Cross' hologram, wearing HEV Mk. 4 suit.

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  Barney boarding tram.

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  Barney banging on door.

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  Gordon passing Barney.

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  Gordon arriving to work.

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  Cross preparing the sample.

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  Magnusson's casserole post-destruction.

The Resonance Cascade

• Just after Gordon Freeman steps into the test chamber, the "G-Man" whispers into Dr. Eli Vance's ear "prepare for unforeseen consequences".
• Beneath the anti-mass spectrometer's chamber, Colette Green brings it online and powers it up to 80%. In the chamber itself, Gordon concurrently starts its rotors.
• The Anomalous Materials team monitoring the experiment's progress power the stage one emitters. Seeing predictable phase arrays, the team activate stage two emitters and, despite the team's objections to Administrator Dr. Wallace Breen, has Gina Cross disengage the safety locks in order to increase power to 105%. Initially concerned by a small discrepancy in their monitoring equipment, it returns within acceptable bounds and the team sustains sequence, informing Gordon the non-standard specimen is ready for standard insertion.
• Gordon pushes the sample into the anti-mass spectrometer, creating a resonance cascade. The team fails to shut down the equipment, and several of its members are injured or killed as the equipment around them explodes. Alien creatures begin teleporting in and out of the chamber from Xen, as does Gordon himself, until he passes out for several hours. Beneath the chamber, doctors Cross and Green too fall unconscious.
• Meanwhile, Barney Calhoun witnesses the effects of the resonance cascade after restoring power to Sector G's main access lift for two stuck scientists, with varieties of Xen lifeforms teleporting into the facility and major equipment malfunctions causing several injuries and deaths. The main access lift fails and falls to the bottom of its shaft, killing the two scientists and knocking Barney out.

• 

  Stage One emitters.

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  Stage Two emitters.

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  Resonance Cascade teleporting Vortigaunts to Earth.

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  Gordon teleported to Xen.

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  Resonance Cascade from Cross' perspective.

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  Ditto, from Barney's perspective.

Remainder of the morning

• Gina Cross and Colette Green regain consciousness. Arming themselves, they fight against alien creatures through the corridors beneath the anti-mass spectrometer to reach doctors Rosenberg and Richard Keller in the control room. While Keller decides to remain to assess the damages received by the equipment, the other three elect to find their way to the surface to call for military assistance.
• The Experimental Propulsion Laboratory was to perform a test fire at 10:30 AM, but this never occurs because of the Resonance Cascade.
• The Cryogenic Safety Crew was to report status at 11:00 AM, but this presumably never occurs because of the Resonance Cascade.

• 

  Beneath the anti-mass spectrometer after the Resonance Cascade.

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  Scene witnessed by Cross and Green on their way to the control room.

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  The four doctors form a plan.

Afternoon

• Gina Cross and Colette Green escort Rosenberg through the ruined Black Mesa Training Facility in order to reach the surface.
• Meanwhile, Gordon Freeman regains consciousness in the anti-mass spectrometer test chamber. With the phone lines cut out, Eli Vance tasks Gordon with getting himself to the surface and seeking help for the science team stranded in the facility.

• Some time after assisting Gordon in the aftermath of the resonance cascade, Vance manages to escape the facility with his young daughter Alyx Vance, who is rescued by the G-Man; Vance's wife Azian perishes during the Black Mesa Incident. Alyx, a family picture and his wedding ring are all he manages to carry out of Black Mesa.

• Cross, Green, and Rosenberg reach the Satellite Communications Center, where they align the satellite uplink dish and send an emergency signal to the military. Cross and Green then make their way back to the Anomalous Materials labs to meet back up with Richard Keller.
• Gordon fights his way through various Xen lifeforms and zombified members of the science team in Sector B's Coolant Reservoir Facility and Sector D's Administration Center.
• During this time, the HECU arrives at Black Mesa, having been ordered by the United States government to kill all alien forces and Black Mesa personnel as containment. This includes Adrian Shephard's unit, whose Osprey is attacked by alien craft. During the chaos, Shephard loses and regains consciousness until the next day.
• By now, Barney Calhoun regains consciousness, fighting through Xen lifeforms and zombies in the tunnel systems of Sector G, searching for a way to the surface.

• 

  Ruined Hazard Course.

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  Ground Zero of the Incident.

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  Vance (right) post-Cascade.

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  Rosenberg contacting the military.

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  Coolant Reservoir Facility post-Cascade.

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  Scientists attempting to escape Administration Center.

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  HECU Osprey attacked by alien craft.

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  Barney's first sight regaining consciousness.

Dusk

• Gina Cross and Colette Green return to Richard Keller, where they re-engage the anti-mass spectrometer's dampening fields in hopes of ending the resonance cascade. The fields fail, with Keller discovering the cause being intentional interference coming from the other side of the rift, speculating the arrival of the alien lifeforms may not be accidental.
• Having climbed his way to Sector D's High Security Materials Storage Area, Gordon Freeman sees his first encounter with the HECU. Briefly reaching the surface only to be forced to descend back into the facility by mortar fire, Gordon is then tasked by a scientist with tracking down the science team taking shelter in the Lambda Complex on the opposite end of the base, as they may be the only ones who can end the catastrophe.
• Meanwhile, having reached the Freight Yard on the surface, Barney Calhoun has his first encounter with the HECU. In the Freight Management Offices he comes across a dying Harold, who advises Barney to rescue Rosenberg, since been captured by the HECU, and has a plan to escape the facility by use of an old prototype of the Lambda Complex's teleporter.
• Keller hatches a plan to create a resonance reversal using the prototype displacement beacon in the Gamma Labs. However, he needs a satellite in orbit before the plan can go through. Personnel in Sector E's High Altitude Launch Center are ready to launch the satellite, but due to a military air traffic lockdown that is in effect they can not. To remove the lockdown, Keller, Cross, and Green travel via the Black Mesa Transit System to the Level 3 Dormitories in search of a security guard with the all-clear codes needed. Here, they have their first encounter with the HECU. Guard found, the group travels to the Black Mesa Air Control facility.
• With the transit system in his location out of action, Gordon is forced to travel through a decommissioned rail system to Sector D's Experimental Propulsion Laboratory, where he destroys three large tentacles sprouting from the base of the silo's tunnel system by firing the rocket engine used in testing.
• Cross and Green fight through several squads of HECU marines and an Osprey and manage to secure Black Mesa Air Control. There they proceed to enter the all-clear codes, lifting the military air-traffic lockdown, and make their way back to Keller to find a way to reach the Gamma Labs.
• Gordon navigates his way through Sector D's tunnel systems and finds himself falling right into a firefight between the HECU and a Gargantua in Sector E's Track Control. Restoring power to the rail system and destroying the Gargantua in the process, Gordon begins his journey through the sector's Materials Transport lines.

• 

  Anti-mass spectrometer dampening lock being reset.

• 

  Facility now under military command.

• 

  M1A1 Abrams tank in the Freight Yards.

• 

  HECU marines in the Level 3 Dormitories.

• 

  Giant tentacles in rocket test silo.

• 

  Osprey at Black Mesa Air Control.

• 

  Battle between HECU and Gargantua.

Night

• Barney Calhoun and Rosenberg make their way to the abandoned Section A-17 Prototype Labs, where a disused teleportation system is being reassembled by doctors Simmons and Walter Bennet. In order for the teleporter to operate accurately, Barney is forced to travel to a ruined Black Mesa research camp on Xen and activate a focuser.
• As Gordon Freeman rides the monorail through the Materials Transport system, he is told by a security guard that he must head up to the High Altitude Launch Center to launch the satellite the Lambda Team can use to reverse the effects of the Resonance Cascade. Now actively being hunted by the HECU, Gordon makes his way back up to the surface and to the launch site. He succeeds in launching the rocket into orbit, but is once again forced to travel back underground.
• Gina Cross, Colette Green, and Richard Keller head to the Gamma Labs on the surface to raise the prototype displacement beacon for activation. Keller is able to reach the main lab, but cannot raise the beacon remotely because of an obstruction. Accessing the lower levels of the labs via the drainage canals, Cross and Green reach the beacon, clear the obstruction blocking it from ascending, and raise it successfully.
• Cross and Green return to Keller in the lab control area, where he gives them the task of activating the beam matrix system that provides the power required for the displacement beacon. After navigating through the Alien Quarantine Labs, they reach the beam matrix and attempt to activate it while simultaneously defending it from alien slaves and grunts rapidly teleporting in. The beam matrix is activated, and the two doctors return to Keller, who makes final preparations for the resonance reversal.
• Cross and Green are forced to defend the displacement beacon against the attacking Xen forces, including an alien craft. In the midst of the battle, both of them are caught in a harmonic reflux. Cross and Green return safely and Keller congratulates them on their success.
• The Black Mesa Hazard Course decathlon was to commence at 19:00 PM in the Level 3 Facility, but this never occurs because of the Resonance Cascade.

• 

  Simmons and Bennet reassembling old teleport system.

• 

  Focuser on Xen.

• 

  Entrance to Materials Transport monorail system.

• 

  Satellite delivery rocket launched by Gordon.

• 

  Alien grunt contained within Alien Quarantine Labs.

• 

  Activated displacement beacon.

May 17

• At some point during the day, Drone Subjects X-8973 and R-4913 are teleported by their leader into Black Mesa to retrieve a crate of Xen crystals which were stolen and used in tests at the facility. They successfully manage to retrieve the crystals from a Black Mesa Research Facility Transport Division vehicle in the Ordinance Storage Facility's parking garage, which had been intercepted by the HECU.

• 

  Xen crystals in the back of the truck.

Morning

• After it is discovered that the teleporter had used its entire supply of batteries to transport him to and from Xen, Barney Calhoun is forced to go down to a power facility and reactivate the generators required to recharge the batteries.
• Finally nearing escape, Barney helps operate the simpler parts of the teleporter to get the three scientists safely on the other side of the portal. Once the scientists escape, the HECU storms the room as he finally teleports himself to the scientists.
• Meanwhile, after encountering an ichthyosaur while searching for an alternate route to the surface, Gordon Freeman reaches a large storage area where he is attacked by Black Ops assassins. After fighting them off, Gordon is hit unconscious by a couple of soldiers. They seize his weapons, and, instead of taking him topside for questioning, drag him to a trash compactor, leaving him for death.
• Barney is teleported to the Black Mesa South Access Tunnel but is caught in a harmonic reflux and is teleported to several locations, including a storage room where he witnesses Gordon being carried off towards a trash compactor. Barney finally teleports back to the scientists, no longer caught in the harmonic reflux. Together, the group manage to successfully escape the facility in a Black Mesa SUV.
• Gordon wakes up and manages to escape from the trash compactor. He stumbles across the now mostly abandoned Biological Waste Processing Plant, making his way through various hazardous machinery before eventually breaking into the Advanced Biological Research Lab.

• 

  Power generators being reactivated.

• 

  Rosenberg escaping the facility.

• 

  Ichthyosaur lurking in a flooded section of Black Mesa.

• 

  Storage complex where Gordon is ambushed.

• 

  Barney witnessing Gordon dragged away by soldiers.

• 

  Barney and team make their way to safety.

• 

  Inside Biological Waste Processing Plant.

Afternoon

• Gordon Freeman rearms himself against the HECU and various Xen creatures running amok in the Advanced Biological Research Lab, searching for a group of scientists with scanner access hiding in the lab who can open the front door.
• Meanwhile, Adrian Shephard regains consciousness in the Black Mesa Medical Lab, saved by scientists unaware of the HECU's mission. He is sent to the crash site of his squad's Osprey to radio for help, where he is told that they are pulling out and he must make his way through the underground transit system to reach the extraction point on the surface.
• Gordon again reaches the surface, now a battleground between the US Military and Xen's forces, the latter turning the tide of conflict in their favor. After scaling the Hydro-Electric Dam, the cliff face of the mesa itself, and the battle-torn Topside Motorpool, he overhears a radio message revealing that the HECU are pulling out and abandoning the base, calling in airstrikes to cover their retreat. Gordon uses a tactical map set up by the military in Waste Processing Area 3 to call in airstrikes to open the blocked underground entrance to the Lambda Complex.
• Concurrently, Shephard reaches the extraction point, hearing the same radio message from the source, by whom he is informed of the HECU's evacuation from the facility. Before he can escape, Shephard is deliberately blocked off by the G-Man closing the hangar door as the last Osprey leaves.
• Gordon fights his way through scores of aliens and the remaining HECU forces in the Lambda Bunker of Sector F before finally reaching the entrance to the Lambda Complex proper.
• Shephard searches for an alternate escape route through several blast furnaces, garages, and offices, meeting up with fellow marines who have also been left behind. By now, Race X have begun their full-scale invasion of Black Mesa, intending to set up Gene Worms to assimilate Earth's natural resources.
• On their way to an underground rail system, Shephard's group are attacked by Black Ops, discovering they have been sent to the facility to execute the remaining science personnel and HECU marines after their failed cover-up of the Black Mesa Incident.
• Gordon reaches the Lambda Complex, forced to flood the reactor core in order to access what is left of the science team, where they inform him he must travel to Xen to kill an immensely powerful being keeping the rift between worlds open.
• Separated from his comrades, Shephard finds himself in the Lambda Complex, witnessing Gordon teleport to Xen. After taking a different portal to the alien borderworld, Shephard acquires the Displacer Cannon, teleporting himself into Black Mesa's Hydrofauna Studies Laboratory.
• At 16:30 PM, Otis Laurey was to have his Security Guard training under security officer Miller's holographic assistant counterpart; this never occurs because of the Black Mesa Incident.

• 

  Alien grunt contained within Advanced Biological Research Lab.

• 

  Crash site of Shephard's Osprey.

• 

  AH-64 Apache patrolling Black Mesa cliffside.

• 

  Evacuation of HECU from Black Mesa.

• 

  G-Man preventing Shephard's escape.

• 

  M1A1 Abrams guarding entrance to Lambda Complex.

• 

  Xen-infested blast furnace.

• 

  Black Ops standing guard outside truck loaded with nuclear warhead.

• 

  Shephard witnessing Gordon teleported to Xen.

• 

Evening

• Arriving in Xen, Gordon Gordon encounters its native species in their natural habitats, as well as the remains of several members of the Survey Team that had come before him. Gordon hops his way across the borderworld in search of his target.
• Traversing through the underwater Hydrofauna Studies Laboratory, Adrian Shephard frees a scientist providing him with information on the area. However, Shephard is forced to teleport to Xen and back again, eventually reaching the Black Mesa Biodome Complex.
• Gordon teleports into the lair of the Gonarch, the mother of the headcrabs, and does battle with the creature. After killing it, he continues onwards to the Xen invasion forces' staging grounds.
• Travelling between various biosphere chambers and laboratories in the Biodome Complex, Shephard eventually reaches Waste Processing Area 3, and receives a radio transmission from a group of marines fighting "some sort of worm creature".
• Gordon navigates through a series of mines and factories, in which the alien slaves are tasked with the preparation of alien grunts, before jumping into the portal found at the top of the production line.
• Shephard encounters a Pit Worm nested in the Toxic Disposal Basin of the waste processing area, using the accumulated toxic waste to kill it. Shephard extends a retractable bridge previously blocked by the Pit Worm, and crosses into the sewers leading to the ruined freight hangars of Sector G.

• 

  Xen ecology.

• 

  Scientist cornered by Pit Drones.

• 

  The Gonarch and her brood.

• 

  Specimen habitats in Biodome Complex.

• 

  The factories of Xen.

• 

  Pit Worm in the throes of death.

Dusk

• Adrian Shephard makes his way through the underground canals and sewers of Black Mesa, fighting through a Voltigore nest before arriving at the Sector G Topside Hydro Plant. Here, a Gargantua has been trapped on top of the dam with several marines attempting to kill it. Shephard uses explosives to destroy the creature and leaves the area through the dam's exposed water pipes.
• Shephard enters an underground parking garage, where he discovers that the Black Ops intend to activate a thermonuclear warhead to destroy the facility. Shephard kills the remaining Black Ops squad in the parking lot and deactivates the thermonuclear device, but later sees the G-Man reactivating it.
• Gordon Freeman is teleported into a vast cavern housing the Nihilanth. Gordon destroys the crystals protecting the massive creature, allowing him to attack its exposed brain. During its death throes, Gordon is teleported to safety. The death of the Nihilanth leads to the liberation of the Vortigaunts from their subjugation under its control.
• Gordon is confronted by the G-Man, the two teleporting across various locales in Xen. The G-Man explains that his "employers" are now in control of the borderworld "for the time being" and have authorized him to offer Gordon a "job". Both are finally transported inside a tram identical to the one Gordon rode to work before the Resonance Cascade, flying through space at immense speed. He is forced to accept the G-Man's offer by stepping through a portal, where the G-Man places him in stasis for nearly 20 years.
• After making his way through warehouses filled with Race X and Black Ops fighting, Shephard arrives at an old industrial area of Black Mesa where an enormous Gene Worm is attempting to come through an interdimensional rift from the Race X homeworld. Shephard uses mounted laser weapons to blind and kill it before it can fully emerge; in its death throes, an enormous portal spreads outwards and envelops Shephard.
• Shephard regains consciousness inside an Osprey flying across the Black Mesa cliffside. While he is confronted by the G-Man, a blinding white flash occurs in the distance as Black Mesa is destroyed by the thermonuclear bomb. The two are transported to Xen, with the G-Man informing Shephard that he will be detained in a secluded location as he is still a dangerous witness. The G-Man departs via portal, leaving Shephard stranded.
• Following the destruction of the Black Mesa Research Facility, GLaDOS' race against Black Mesa is concluded.

• 

  Gargantua trapped on the Hydro-Electric Dam.

• 

  Black Ops preparing the bomb.

• 

  The Nihilanth in its chamber.

• 

  Ditto, in its final moments.

• 

  Depiction of the newly-freed Vortigaunts.

• 

  G-Man offering Gordon a "job".

• 

  The Gene Worm entering Black Mesa.

• 

  G-Man detaining Shephard in the Osprey.

May 18

• At 8:00 AM, Colette Green was to conduct a Public Relations Tour; this never occurs because of the Black Mesa Incident.

• 

Combine Invasion of Earth

• Portal Storms rage on Earth while Xen fauna continue to be teleported across the globe. Attempts to explain the storms vary, ranging from the meteorological consequences of climate change, to clandestine scientific experiments.
• The Combine launches its assault on Earth, with global military forces resisting despite being clearly outmatched by the Combine's resources and technology. Untold humans lives are claimed by the war in a mere seven hours as cities are torn apart by enemy forces. Dr. Wallace Breen is able to make contact with the invaders, and on behalf of the United Nations surrenders the entirety of planet Earth, with all its states and peoples, to the Combine. Breen is appointed Earth's Administrator, responsible for controlling the population under Combine rule. These events prompt speculation that the recent Portal Storms may have been an intentional prelude to an attack; there is little consensus on any of the unprecedented events, but some prominent biologists and zoologists believe the Combine to be a species distinct from the lethally aggressive "portal creatures".
• Portal Storms continue as millions are left in desperate need of food and shelter as existing food supplies sit idle, unable to reach their destinations due to disruptions and lack of coordination. Experts warn that preventable deaths will occur if the situation continues, advising members of the public to remain in their homes and avoid falling prey to panic. Federal emergency response officials encourage citizens to rely on their own existing food and water stockpiles before making use of government food banks. Militaries, U.N. peacekeeping forces, and volunteer militias are stretched to their breaking point as the storms rage on. Musical superstars join forces to celebrate the lives of the fallen and issue a call for interplanetary peace and cooperation with the "EarthAid Unite" concert broadcast on the weekend.
• Scientists remain unable to offer any solution to the ongoing portal storms devastating cities worldwide, nor are they any closer to determining how to predict when new portals will appear. Contrary to early speculation, however, there is a growing consensus that the storms have not been instigated by the Combine forces; experts note that the "portal creatures" and the Combine appear to be adversaries.
• Stock values plunge in the wake of the Combine's assault on Earth, with most major markets having now closed until further notice. Markets in New York, Shanghai, Hong Kong, London and continental Europe have suspended trading. Communication lines out of Japan are largely inactive, leaving the status of Tokyo's stock market unknown, but assumed to be closed. The U.S. Securities and Exchange Commission says that it does not expect trading to resume for the foreseeable future, given the extreme global uncertainty and instability.
• Breen faces criticism for his role in humanity's surrender, with critics accusing him of rank opportunism and pointing out that since no concessions were extracted in the negotiations with the Combine, humanity has no leverage over them whatsoever, allowing the Combine to make as many further demands as they wish. Some remain sympathetic to Breen, however, arguing he took the only possible course of action given the extreme nature of the situation.
• The Aperture Science Enrichment Center remains in lockdown with employees still trapped inside, diminishing to only a few left. Last surviving employee Doug Rattmann manages to avoid captivity as a result of his paranoid schizophrenia. After weeks of evading GLaDOS' constant attempts to capture him, he manages to gain access to her Test Subject files and research the reports of rejected candidates, including Chell, who was rejected for testing due to her high tenacity. On a hunch that Chell's abnormal stubbornness might allow her to defeat GLaDOS, Rattmann tampers with the Test Subject roster, rearranging it so that Chell's name is at the top. From this point on, Rattmann hides in unused portions of the facility, where GLaDOS is unable to monitor him.

• 

  A Portal Storm.

• 

  United Nations Secretariat Building in New York City during the Seven Hour War.

• 

  Front page of The Times on the day following the Seven Hour War.

• 

  Front page of The Terminal following the Seven Hour War.

• 

  Front page of 7 days following the Seven Hour War.

• 

  Breen featured on the cover of Tech Impact, 200-.

• 

  Newspaper clippings of this period.

• 

  Rattman placing Chell at the top of the Test Subject roster.

Between 200- and 202-

• Earth's ecosystems are contaminated by alien fauna, flora and radiation. The Combine activates a field suppressing human reproduction and introduces a chemical into the water supply causing forgetfulness. The remaining human population are relocated to numbered cities devoid of their original names, where they are systematically oppressed to prevent any interference with the Combine's overarching objectives. Human soldiers are assimilated into the Combine Overwatch and assigned to distinct "sectors" designated around an urban center.
• Surviving Black Mesa personnel, including Barney Calhoun, Isaac Kleiner, Arne Magnusson, and Eli Vance and his daughter Alyx, relocate to the new Earth capital, City 17 (during which Dr. Vance loses his left leg to a Bullsquid while helping Kleiner climb over a barrier to get into the city ), where they continue researching interdimensional teleportation with the hope of freeing Earth from the Combine's rule, and contribute to founding the local Resistance movement. While working with Judith Mossman on teleportation at Black Mesa East, Dr. Vance designs the Zero Point Energy Field Manipulator and rebuilds a Scout Car with Alyx for the Resistance outposts located along the Coast, on which he mounts a Tau Cannon. During this period, Dr. Vance becomes the first human to make peaceful contact with the Vortigaunts, quickly persuading the alien race to ally with humanity against the Combine.
• Alyx Vance grows up under Combine rule, living in and around City 17, with Dr. Vance building Dog to protect her. As she reaches adulthood, Alyx begins working as a core member of the City 17 Resistance, helping Citizens escape the city to Black Mesa East through the old canals, and assisting her father, Kleiner, and Mossman establish a teleport connection between Black Mesa East and Kleiner's Lab.
• Ravenholm, a former coastal mining town in the Wasteland, is discovered and occupied by the Resistance and refugees fleeing from City 17. The town remains under the radar for some time until it is eventually discovered by the Combine, leading to a massive Headcrab Shelling, completely overrunning the town and turning most of its population into zombies. Being linked to Black Mesa East via tunnel, the entrance to Ravenholm is sealed to prevent zombies from escaping. The only survivor of the shelling, Father Grigori, descends into madness, remaining in the town and constructing various deadly traps to liberate his 'congregation' from their zombified states through death.
• Kleiner's teleporter is tested on a cat, but the experiment is a failure, resulting in a macabre fate for the animal that would traumatise Barney for years to come. Work on the device continues until Gordon Freeman's return.

• 

  Globe marked following the Combine's invasion.

• 

  Xen infestation in City 17's Quarantine Zone.

• 

  Civil Protection conducting a sweep.

• 

  Photo of a young Dog.

• 

  Headcrab Shell near Ravenholm Cemetery.

2010s

201-

• Arne Magnusson begins work on the White Forest satellite delivery rocket.

• 

"Around" 2010

• A short amount of time after the Combine invasion of Earth, somewhere around the year 2010, in the Aperture Science computer-aided Enrichment Center, Chell is awoken by GLaDOS who forces her to perform seemingly routine tests. However, Chell soon learns that the Aperture employees are long dead or escaped, and that GLaDOS is seemingly the only being left in the decaying facility. After much promise of cake at the test's conclusion, Chell is met with an incinerator, which she narrowly escapes, and works her way through the maintenance areas, despite GLaDOS' protests. Eventually, Chell finds GLaDOS' control room, and manages to escape death by neurotoxin by detaching GLaDOS' Personality Cores, and partially destroying her as a result. Chell is forced to the surface by GLaDOS' explosion, only to be dragged away from freedom and back into the facility by the Party Escort Bot. Unknown to Chell however, GLaDOS is still alive.
• Doug Rattmann, the last Aperture employee alive, witnesses GLaDOS' destruction. After the Party Escort Bot drags Chell back into the facility, Rattmann feels guilty for Chell's situation and reenters the facility to help her. At the beginning of her stasis, Chell is under Rattman's supervision.
• Fifty days after she was put back in stasis, Chell is awakened within an Extended Relaxation Chamber by an unidentified announcer. In compliance with "state and federal regulations," Chell is instructed to perform a mandatory physical and mental wellness exercise before ultimately returning to bed.
• GLaDOS' partial destruction is followed by a period of inactivity within the Enrichment Center, during which time maintenance systems and Personality Cores maintain its functions. The facility remains in disarray, having become overgrown and dilapidated. Pre-recorded 'Emergency Test Protocols' can oversee test chambers in times of cataclysmic system failure, "remain[ing] functional in apocalyptic, low power environments of as few as 1.1 volts. Chell spends this time in stasis for roughly 50,000 years.
• Despite all that has occurred to both the outside world and the Aperture Science Enrichment Center, the company receives a purchase order on January 25 for a blue sentry turret from a T. Reidford. The order will not begin preparation for roughly 50,000 years.

• 

  GLaDOS' remains on the Aperture Laboratories parking lot shortly before Chell is dragged away by the Party Escort Bot.

• 

  Rattmann seeing Chell being dragged away by the bot.

• 

  Inside of Chell's Relaxation Chamber.

• 

Between 2015 and 2024

April

• By now, the Citadel has begun construction. As described in Alyx's observations, the initial spire structure appears from the center of a deep crater in the ground, and a perpetual storm rages above the structure.

• 

  Alyx Vance's monitoring of the Citadel's construction.

June

• Some sort of scaffold and feeder cables appear around the main structure of the Citadel. A perimeter wall is built surrounding the crater at the bottom of the structure, and a "flight deck" and oscillating "ribs" appear near the top of the tower. The storm above seems less aggressive, but the top of the tower is still shrouded by clouds. The purpose of the Citadel remains unknown.

July 19

• An unidentified green jar in Alyx's Hideout is dated to this day.

• 

November 29

• Alyx details her most recent observations of the Citadel's construction. She observes lights coming from the tower as some sort of power source appears in the center - this "mini reactor" appears to be inconsistent and self-contained, often causing blackouts. It seems to draw power from the Citadel's new power source. The scaffolds around the tower appear to be mobile. More cables appear daily.

• 

  The Citadel at the beginning of Half-Life: Alyx.

On or after November 29

Morning

• While recoinnoitring on the Citadel's construction process, Alyx Vance notices troops moving supplies into the Quarantine Zone. She reports her findings to her father Eli and Resistance member Russell as they perform a heist of a Combine mini-reactor, catching sight of a strange floating structure before cutting off. This triggers a massive manhunt that results in the capture of both Alyx and Dr. Vance. Russell manages to rescue Alyx and leads her to his lab, warning her that the Combine will transport Dr. Vance to Nova Prospekt for interrogation. He formulates a plan for Alyx to intercept the train carrying Dr. Vance at Fairview Junction. Once geared up, Alyx embarks on a journey to save her father.
• Alyx is forced to venture further on foot after her train stops outside of the Quarantine Zone. After meeting the eccentric Vortigaunt hermit Gary, Alyx agrees to help free his imprisoned kin, who are being used as biological batteries to keep the vault structure afloat, and she is instructed to "look to the Northern Star".
• After making her way through the Drainage Tunnels, Alyx finally arrives at Fairview Junction, battling the Combine forces there and managing to derail the Razor Train carrying her father. After being rescued by Gary, Dr. Vance informs Alyx of a Combine "superweapon" stored in the Vault, prompting her to find and infiltrate the Vault and steal the weapon before it can be relocated.

• 

  Russell using a holographic map in his lab to explain his plan to rescue Dr Vance.

• 

  Entrance to the City 17 Quarantine Zone.

• 

  A squad of Combine Grunts caught by Barnacles in the Drainage Tunnels.

Afternoon

• Gary escorts Eli Vance back to safety as Alyx Vance continues to navigate through the Terminal Gardens Metro Station. She identifies multiple substations linked to the Vault via cables which need to be subdued in order to bring it down, and after being ambushed by a Combine squad, she realizes that the Northern Star is a real hotel housing one of the generator substations supporting the Vault.
• Alyx enters the infested Northern Star hotel and makes her way towards the substation. Eventually, Alyx manages to destroy the cables connected to the Vault and disable the substation, discovering an enslaved Vortigaunt within. Grateful for its freedom, the liberated Vortigaunt promises Alyx to rally its peers to take down the remaining substations. She then leaves the hotel and proceeds towards the Vault as Combine troops begin to actively pursue her.

• 

  Entrance to the Terminal Gardens metro station.

• 

  Exterior of the Northern Star hotel with a Combine substation attached to it.

Dusk

• Alyx Vance enters the Holden Company Processing Plant, witnessing the Vortigaunts taking down another substation on the way. After engaging with more Combine troops and getting past a room filled with explosives, she enters the Golden Lion Distillery, hoping to find a route to get across to the Vault indirectly.
• Inside the distillery, Alyx meets a human survivor, Larry, who is stranded with a mutated Combine Hazmat Worker nicknamed "Jeff". Alyx finds a Combine seal that needs to be lifted in order to proceed, and she carefully maneuvers her way around the distillery looking for three batteries to power the seal while avoiding Jeff, ultimately tricking him into a trash compactor. After opening the seal, she then heads down into the tunnel underneath, discovering evidence of Antlions present in the area.

• 

  Vortigaunts successfully taking down another substation.

• 

  Alyx's first encounter with Jeff, who is roaming the distillery.

Night

• Alyx Vance finds herself inside the Antlion-infested Central Zoo, fighting her way through swarms of Combine soldiers and the aliens. Eli Vance contacts Alyx to warn her that the Vault is, in actuality, a prison containing something or someone that even the Combine fears. Alyx continues onward, determined to retrieve whatever resides within the Vault.
• After the deactivation of the last Combine substation, a backup device is triggered to prevent the Vault from falling, prompting Alyx to immediately head toward it. After fighting through another swarm of enemies, she spies an unidentified woman addressing a Combine Advisor. The woman urges the Advisor to move the Vault away as quickly as possible, mentioning that the structure contains a survivor of the Black Mesa Incident who wreaked havoc and "then disappeared". Eli deduces that the woman must be referring to Gordon Freeman, and tells Alyx it is of utmost importance that he is freed.
• Alyx finally arrives at the backup station and attempts to dock the Vault to the station to no avail, causing it to collapse onto the city below. She awakens in the debris and ventures down into a destroyed parking garage, causing a deactivated Strider to regain consciousness and engage with her as she restores power to a nearby elevator. After defeating the Strider, Alyx leaps into a green beam and ascends into the vault.
• Boarding the Vault, Alyx finds herself in an abandoned apartment complex which the structure was built around. She navigates through the paranormal contents of the Vault, fighting the last bastion of Overwatch soldiers stationed there using Vortigaunt energy absorbed by her gloves. After defeating the soldiers, Alyx discovers a strange prison cell in the center of the Vault which she then breaks open, releasing the G-Man. The G-Man makes an offer to Alyx, showing her a vision of the future where her father is killed by a Combine Advisor. The G-Man allows Alyx to intervene, saving Eli and killing the Advisor, but it comes at the cost of her freedom as she is then "hired" by the G-Man and put into stasis against her will.

• 

  Sentry Guns firing on an Antlion at the entrance to the Central Zoo.

• 

  Alyx observing the Scientist speaking to a Combine Advisor.

• 

  Alyx using a mounted gun against the Strider.

• 

  The exterior of the icosahedral cell of the Vault.

• 

  The G-Man making an offer to Alyx.

Between 2019 and 2028

• This is the last time Alyx Vance drives Highway 17 with the Scout Car. During the summer, she leaves the car with Leon at Shorepoint Base.

• 

  Shorepoint, with the Scout Car on Pier 87.

2020s

202-

Day 1 of Freeman's return

• Approximately two decades post the Black Mesa Incident, sometime in autumn, the G-Man rouses Gordon Freeman from stasis, inserting him into a train bound for City 17. Gordon encounters Barney Calhoun, who instructs him to navigate to Kleiner's lab; on the way there, Gordon unwittingly becomes embroiled in a Civil Protection raid before being rescued by Alyx Vance.
• At Kleiner's lab, it is decided that Gordon and Alyx should be teleported to Black Mesa East. After Gordon receives the Mark V HEV Suit, Alyx is teleported to Black Mesa East successfully; when trying to teleport Gordon, however, a malfunction causes him to teleport to various random places, including Breen's office in the Citadel. Gordon is forced to head on foot to Black Mesa East by himself as the Citadel is placed on high alert, with thousands of Overwatch units being deployed across City 17 in an effort to destroy all known resistance bases in Gordon's path and halt him.
• Gordon travels through the underground railroad as the few resistance shelters he finds are quickly raided by Civil Protection. He engages in combat with Civil Protection forces and Xen fauna before arriving at Station 6, where he acquires an airboat.
• Aboard the airboat, Gordon is pursued through the Canals by hundreds of Overwatch units. Eventually, after stopping at several Civil Protection outposts and dispatching of a Hunter-Chopper above the dam at Port 5, Gordon reaches Black Mesa East.
• Gordon meets Judith Mossman for the first time and is reunited with Eli Vance, along with Alyx. Alyx takes Gordon to the scrapyard in order for him to practice with the Gravity Gun. While Gordon is playing with Dog in the scrapyard, Alyx spots Combine Scanners sweeping the area, shortly before an all-out aerial raid on Black Mesa East. While attempting to rejoin the others, Gordon and Dog are separated from Alyx, and Gordon is forced to escape down the tunnel to Ravenholm.
• Gordon makes his way through Ravenholm at night and meets with Father Grigori, who guides him through the town. After battling through hordes of zombies, Gordon makes his way into the mines connecting to the coast.

• 

  The City 17 Trainstation Plaza.

• 

  Alyx teleporting to Black Mesa East.

• 

  The aftermath of the massacre on Station 1.

• 

  A Hunter-Chopper passing by Station 7.

• 

  The front docks of Black Mesa East, concealed by a generating station.

• 

  The courtyard of Ravenholm's entrance.

Day 2 of Freeman's return

• Gordon Freeman exits the Ravenholm mines in the morning, fighting alongside Resistance fighters in a shootout against a squad of soldiers. Gordon is informed by Alyx Vance via radio that Eli Vance has been captured and taken to Nova Prospekt, and so Gordon sets out on a journey along Highway 17 to rescue him.
• Travelling along the coast, Gordon stops by at several abandoned outposts while evading swarms of Antlions before eventually reaching New Little Odessa, where he meets Colonel Odessa Cubbage and helps fend off a Combine Gunship before departing for Lighthouse Point. After crossing the railway at Point Bridge, Gordon arrives at Lighthouse Point.
• At Lighthouse Point, Gordon helps the rebels hold off several squads of Combine Overwatch forces. Proceeding through a cliff path, he carefully avoids disturbing the Antlions buried beneath the sand, eventually coming across the Vortigaunt Camp. After being taught to use Antlion pheropods, Gordon fights his way along the beach towards Nova Prospekt.
• Gordon breaches Nova Prospekt's defenses, making his way towards the facility's train depot. He rendezvous with Alyx Vance at the depot and begins to search the facility for both Dr. Vance and Judith Mossman, after discovering that she has been collaborating with the Combine. Alyx hatches a plan to use the Combine teleporter to transport themselves to safety at Kleiner's Lab; however, Mossman seizes the opportunity to escape with Eli to the Citadel. Alyx and Gordon escape through the teleporter as soldiers swarm the room, but due to a slow teleport sequence, it will take them over a week to return to Kleiner's Lab.
• The destruction of Nova Prospekt and the Combine's only teleporter prompts the Resistance to launch an uprising against the Combine in City 17.

• 

  The dry seabed at Dock 137.

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  Combine Bunkers overseeing the beach below Nova Prospekt.

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  The Nova Prospekt compound.

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  The Combine teleport in the lower levels of the Depot.

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  Heavily damaged street during the Battle of City 17.

"Over a week" later

• Gordon Freeman and Alyx Vance return to Kleiner's Lab after teleporting away from the depot. Gordon goes on to help Resistance fighters in the uprising, while Alyx remains in the lab to help Isaac Kleiner escape the city. Later, Alyx returns to help Gordon but is captured by Combine soldiers and taken to the Citadel.
• Gordon teams up with Barney Calhoun, together leading a battle at the Overwatch Nexus and disabling a generator powering a suppression device that is hampering resistance attacks, eventually fighting their way to the foot of the Citadel. There, they encounter Dog, who provides a pathway to allow Gordon to pass through into the Citadel.
• After making his way into the Citadel, Gordon fights through large numbers of Combine soldiers as Wallace Breen attempts in increasing desperation to convince Gordon to surrender. Gordon is forced to enter another Stalker pod and is quickly discovered on camera, transferring him to the top of the Citadel directly to Breen's office.
• Inside Breen's office, Gordon is reunited with Eli Vance and Alyx, who are both being held captive as well. Breen prepares to send Gordon, Alyx, and Dr. Vance through a portal to the Combine Overworld until Mossman intervenes and releases them. Breen attempts to escape as Gordon gives chase, arriving at the portal atop the Citadel just before it fully opens. Gordon attacks the reactor, causing it to fail and go critical; just as it explodes, the G-Man freezes time and addresses Gordon, congratulating him on his success and stating that he has received "interesting offers" for Gordon's services. Gordon is put back into stasis, along with Alyx.
• Dr. Vance and Mossman leave the Citadel, with Vance shortly arriving at White Forest. Mossman travels north of City 17 with her team to attempt to track down the Borealis.

• 

  Resistance fighters standing guard inside a damaged underground road tunnel.

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  Combine Overwatch forces preparing for battle.

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  Combine Prisoner Pods being transported within the Citadel.

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  The G-Man arriving to place Gordon back into stasis.

A few days later

• Gordon Freeman and Alyx Vance are rescued from atop the Citadel by several Vortigaunts, who remove them both from stasis against the G-Man's wishes. After Gordon and Alyx reunite, they are informed that the Citadel Core is at risk of exploding at any moment, and so they re-enter the Citadel to try to reactivate the stabilization mechanism for the core in order to avert disaster.
• Gordon and Alyx are successful in re-engaging the reactor's containment system, delaying the explosion. Alyx subsequently discovers that the Combine are trying to use the reaction to send a message to off-world Combine forces for backup, and the pair receive a transmission from Judith Mossman in the arctic, where she discusses the "Project" which she and her team had discovered, before being cut short as the Combine attacks the base. Alyx makes a copy of the message packet to take to Kleiner and Dr. Vance.
• Alyx and Gordon then board a Razor Train to escape the Citadel, before the train unexpectedly derails. After escaping from the wreckage, the pair fight through the abandoned underground parking garages and tunnels of the city together, searching for a way to the surface.
• Eventually, the pair manages to find the exit of an underground train station and they arrive at the surface, reuniting with Barney Calhoun and a group of survivors who are preparing to move on a train station in order to escape the city. Gordon and Alyx split up from the group to draw the remaining Combine forces away from the refugees.
• Upon reuniting with Barney again at the Technical Trainstation, Alyx and Gordon work to move the Citizens to the trains while facing increasing Combine opposition. After battling Combine soldiers and a Strider, the duo reprogram another train and board the caboose. As the Citadel nears its final moments, the Combine successfully manage to transmit a signal back to the Combine Overworld before City 17 is destroyed in the ensuing explosion.

• 

  The G-Man being halted by the Vortigaunts.

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  Alyx contacting her father after finding Gordon beneath the rubble.

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  Drop-down view of the Citadel Core.

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  Dead Zombines inside a crashed Razor Train.

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  A Strider among City 17 rubble.

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  The destruction of the Citadel.

The next day

• Gordon Freeman and Alyx Vance emerge from the trainwreck. A superportal has begun forming above the collapsed Citadel. Travelling through an infested mine tunnel to a communication building, Alyx is able to contact White Forest base to try and deliver their data packet. Shortly afterward, Alyx is critically wounded by a Hunter, but a Vortigaunt arrives in time to drive off Antlions and stabilize Alyx's condition. Gordon becomes separated from Alyx and the Vortigaunt and must travel through Antlion caves to meet them at a nearby Resistance outpost.
• Gordon arrives at a small Resistance outpost within the mines where Alyx has been brought. After fending off swarms of Antlions, Gordon and the Lone Vort are forced to travel deeper into the caves to retrieve an Antlion larval extract, which they deliver just in time for Alyx to be healed. During the healing process, the G-Man contacts Gordon, asking him to escort Alyx to White Forest safely and instructs her to tell her father to "prepare for unforeseen consequences." After Alyx has recovered, she and Gordon, accompanied by the Lone Vort, proceed to the surface.
• Alyx, Gordon, and the Lone Vort reach the surface, observing a large group of Combine forces traveling north towards White Forest before Gordon kills the Antlion Guardian. Gordon descends into the last Resistance outpost of the Victory Mine to retrieve a working muscle car. After bringing the vehicle back to Alyx, the pair depart.
• Gordon and Alyx proceed to White Forest. After defeating a Hunter ambush at a radio tower, Alyx and Gordon attempt to contact White Forest base, but are unable as Advisors appear to be blocking the transmission. Continuing, they investigate a nearby barn and discover an Advisor encamped inside it. As it flees, the pair are caught in another Combine ambush and are pursued by a Hunter-Chopper to the next Resistance outpost.
• After the helicopter is destroyed, Alyx and the rebels work on repairing the car while Gordon disables a Combine Autogun that is hampering Resistance movement. After the car is fixed, Alyx and Gordon continue to White Forest. An enormous Combine ambush is laid for them at the White Forest Inn, but after defeating the attacking Overwatch forces, they approach the White Forest base. After watching Dog defeat a Strider awakened from a downed dropship, Gordon and Alyx finally arrive at White Forest.
• Alyx delivers the transmission packet to Eli Vance and Isaac Kleiner. Gordon and Alyx learn that the White Forest team is preparing a special rocket which they plan to use, in conjunction with Alyx's data packet and the satellite array launched during the Black Mesa Incident, to close the Combine superportal. After repelling a Combine attack, Gordon and Alyx return to Kleiner and Dr. Vance, who have completed decoding Judith Mossman's message, in which they discover her findings about the Borealis. Alyx delivers the G-Man's message to her father, much to his shock. They are soon interrupted, however, as they are informed of a larger Combine attack force advancing on the base. Gordon manages to defeat the attack force in the valley around the base.
• The Resistance's rocket is successfully launched, closing the superportal and preventing the Combine from calling in reinforcements from their homeworld. However, as Gordon and Alyx prepare to depart to search for Mossman, Advisors attack the helicopter hangar. As an Advisor is about to kill Dr. Vance, the G-Man allows Alyx from five years ago to travel forward in time to this point in order to kill the Advisor before it kills her father. Alyx of the present is then taken by the G-Man. Eli becomes furious when he realizes that she was taken by the G-Man and vows to kill him.

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  The wreckage of City 17.

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  Alyx Vance attacked by a Hunter.

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  The G-Man's "heart-to-heart" with Gordon.

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  The Muscle Car above the last Victory Mine outpost.

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  The Barn Advisor pulling on Alyx Vance, Gordon Gordon and a dead Rebel.

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  The White Forest Inn exterior.

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  Strider being destroyed by a Magnussson Device.

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  The White Forest rocket lifting off.

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  Dr. Vance hands Gordon his crowbar after vowing revenge against the G-Man.

Far Future

Circa 52,000s

• After over 50,000 years in stasis, Chell is awoken by the personality core Wheatley. Wheatley insists he can secure an escape route out of the Aperture Laboratories, which instead results in the inadvertent reactivation of GLaDOS. Chell is forced to make her way through new test chambers controlled by GLaDOS, eventually managing to escape the test chambers with Wheatley's help. After disrupting the facility's Turret Redemption Lines and Neurotoxin Generator, they make their way to GLaDOS' chamber and confront her. With Chell's help, Wheatley performs a core transfer with GLaDOS and takes control of her body, gaining control of the entire facility. However, after being corrupted by his new power, Wheatley experiences a fit of rage, transferring GLaDOS into a potato battery and slamming her and Chell down into the lower depths of the facility. Chell finds herself traversing old condemned Enrichment Spheres originating from the mid-20th century, at which time Aperture Laboratories was under the direction of Cave Johnson. After reuniting with GLaDOS, the pair continue to traverse through the old facilities until they reach the top of Aperture Science, where they discover that Wheatley has been mismanaging the facility, almost leading to a nuclear meltdown before a standoff between Chell and Wheatley results in Wheatley being trapped in Earth's orbit. GLaDOS regains control of her body as Chell falls unconscious.

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  Chell's Relaxation Chamber, now visibly damaged.

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  GLaDOS awakens in her ruined chamber.

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  Turret Redemption Line.

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  Chell discovers the now potato-powered GLaDOS in a crow's nest.

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  Chell and GLaDOS facing Wheatley.

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  Wheatley with all the cores placed.

The next day

• After Chell awakens the next morning, GLaDOS deletes Caroline's consciousness from her brain and says her final goodbyes to Chell, sending her outside.
• Shortly after Chell's departure, GLaDOS turns onto testing two testing androids, ATLAS and P-body. They are assigned to carry out a series of tests in six different courses; at the end of each course, GLaDOS sends the androids outside of the testing chambers and into the facility itself to help her regain control of the facility. After all the courses are finished, GLaDOS is able to access a vault in the lower levels which contains hundreds of human test subjects. She has determined that, given their inability to die, ATLAS and P-body aren't as fun to test with as human test subjects. Once they open the vault, GLaDOS claims to have more work for them as she destroys them.
• Over the next week, GLaDOS resumes human testing; however, this ultimately results in the death of every remaining test subject in the facility.

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  Back exit of Aperture Laboratories years in the future.

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  The Hub.

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  Inside the Human Vault.

One week later

• GLaDOS rebuilds ATLAS and P-body, guiding them through a new set of courses as she attempts to cover up a number of mechanical failures. Eventually, the Reassembly Machine fails, forcing ATLAS and P-body to make a detour through an incomplete test track. After revealing what happened over the past week, GLaDOS sends the pair down to an old mainframe chassis, where she believes that Chell has returned and has gained control over the machine. Entering the final chamber, ATLAS and P-body find that the mainframe is being controlled mindlessly by a nesting crow, which ATLAS manages to shoo from the control panel. After P-body manages to lock the bird out of the facility, GLaDOS notices that it had been harbouring three eggs, which she hatches in an "oviparous warming vault," planning to breed the chicks as "little killing machines".

• 

  The three crow chicks under GLaDOS' care.

See also

• Canon
• Retcons