Half-Life storyline



This article describes the Half-Life storyline, chapter by chapter.

Hazard Course (optional)


"Hello, and welcome to the Black Mesa Hazard Course"

- Holographic Assistant

The Training Facility at Black Mesa houses the Hazard Course to help users of the HEV Suit hone their skills at jumping, crouching, and combinations of both movements in an environment.

Trivia

 * In Opposing Force, the player can visit the Hazard Course at the duck-jump training room by using the Displacer Cannon in Xen, where Adrian Shephard first acquires it. The room appears to be functional despite the Xen invasion, as the Hologram and success markers still work. A nearby Vortigaunt mistakes the Hologram for a real person and attacks it. It soon realizes that the Hologram is fake and proceeds to attack the player.
 * In Half-Life: Decay, one of the chapters happens to be Hazardous Course, in which Doctors Colette Green and Gina Cross walk through the destroyed remains of the course. The Hologram in the course is Gina Cross, one of the main characters in Decay.
 * In Half-Life, if the player kills a Scientist at the end, the turrets won't deploy but the nearby Security guard will attack the player for killing a Scientist. In Half-Life: Source, the turrets will deploy if the player kills either the scientist or the guard.
 * Although it says in the Half-Life: Decay instruction manual that Gordon went through this at 7:30 on May 16, Marc Laidlaw has retconned this by saying that this occurred quite a while before the Black Mesa Incident, on one of Gordon's first days at work.

Chapter 1: Black Mesa Inbound


"This train is inbound from Level 3 Dormitories to Sector C Test Labs and Control Facilities"

- Black Mesa Announcement System

Gordon Freeman rides the tram to his underground lab at 8:47AM; little does he realize that it is the calm before the storm. The public announcement system announces the most recent news, making ironic comments about hazardous substances and urinalysis tests, as disturbingly large pools of radioactive waste pass by him. Doors clunk open and close again behind him as he goes slowly underground to the test chamber. From the windows, Gordon can see nuclear missiles ready for transport to launch sites, robots nearly crashing into the tram, and the intricate workings of the Black Mesa Research Facility revealing themselves as being fragile, and more often than not, broken. Bashing on a locked door, Barney Calhoun passes by as Gordon silently continues his trip.

At a Loader crossing, the tram is stopped, and on the left, a mysterious man in a blue suit stares blankly past him. Eventually, the tram reaches its destination, and after stepping out onto the precarious catwalk, Gordon's day only just begins.

Trivia

 * This chapter features the only confirmed sighting of Barney Calhoun in Half-Life, affirmed by the beginning sequence to Half-Life: Blue Shift
 * Marc Laidlaw never confirmed that Barney Calhoun from Half-Life 2 is indeed the same from Half-Life: Blue Shift, but the fact that the second one is called by "B. Calhoun" suggests that they are the same person.
 * Due to the fact that Barney's tram ride lasts less than 5 minutes, Half-Life must either begin in late 8:46, the time changing as the Black Mesa Announcement System is speaking, or Barney Calhoun lingered in the tram for a while before getting out.
 * The time at which the chapter ends depends on the amount of time it takes for the player to get between the two doors in which the new chapter's first map loads. It is more likely that the canon time for the end of the chapter is 8:52, as Gordon is already running late.
 * In the penultimate map of this chapter, it is possible to see a different version of the Sector C Test Labs entrance behind the door by using cheats or external map viewers.
 * Though Mark Laidlaw, the in-house writer for Valve Studios, has never directly stated the year in which the "Black Mesa Incident" occurs, upon investigation it could be concluded that it most likely happened sometime in 2000 or 2001. This conclusion can be met by taking the following clues into consideration:

1. As you make your way through the facility, you will find a calendar hanging on the wall in a storage closet which reads "December", and lists the 31st day of the month as falling on a Sunday. In the new millennium, this only occurred in the years 2000, 2006, and 2011. However, Marc Laidlaw has stated that this does not mean anything.

2. The final clue is a Black Mesa Jeep Grand Cherokee, which has been identified as being either a '97 or '98 model.

Since it is unlikely that a highly funded, secret government facility would be using a vehicle that was between eight and thirteen years old, and due to the fact that there are many examples of technology from the early 90s, such as VCRs and CRT monitors, seen throughout the facility, it is most likely to have happened during that time.

Chapter 2: Anomalous Materials


"They are waiting for you Gordon... in the Test Chamber"

- A scientist reminds Gordon of his duty

Arriving at the Anomalous Materials Laboratory, his usual place of work, Gordon dons his HEV Suit and checks his locker, as per routine. Continuing down to the lab once more, Gordon finds himself face to face with the people conducting his test.

They inform him that they have a unique and large sample of anonymous origin, and that they will be deviating from normal procedure to accommodate for this. Carrying on through more doors and past more scientists, he enters the chamber, and the large metal door closes behind him.

Following the normal procedure, he goes up the ladder to the control panel and presses the button to start the rotors on the excessively huge Anti-Mass Spectrometer suspended from the ceiling. Going back down, he waits for the sample to arrive in its cart. Rising up from below, the sample arrives at last. "Standard procedure for a non-standard specimen," they assure him from above. "Go ahead, Gordon." Taking the cart in hand, he pushes it nonchalantly into the beam.

All that happens next became something of a blur. Screaming from the scientists, telling him to stop, but drowning that out, the deafening sound of explosions, and flashes of green light that leave fading marks on his retina. Then black. All that can be heard is the sound of his heavy breathing. Another flash of green, and he's on a strange alien world. Just within the pool of green light around him, odd-looking bipedal lifeforms stare at him, confused about why he's there. More so, Gordon wonders where he could possibly be. Another flash of green and he's back in the destroyed test chamber, feeling considerably worse for wear after his entirely other worldly experience - but it's certainly not over yet.

Trivia

 * At the beginning of the chapter, behind the desk where the security guard is sitting, there is a red and green switch. If used, it will momentarily set off an alarm. If this happens, a scientist and the security guard will scold Gordon.


 * In the same room the security guard is sitting, there is a small set of machinery in the lower left corner. There is a red and a green button on the front of it. Upon pressing the use key on either of them (they are part of the same model), a laptop folds out on top of the set of machinery. The owner of the laptop,a scientist,sees this and scolds the player,saying he's "expecting a very important message" and closes the laptop and locks it, preventing Gordon from using it.


 * In another area, there is a light switch that can be used to turn off the lights. A scientist will take note and shout "My God, what are you doing?" and proceed to turn the power back on.


 * In this chapter, random security guards may say "Hey, catch me later, I'll buy you a beer!" upon interaction. In Half-Life 2,when you meet Barney Calhoun, a former Black Mesa security guard, he will say "Now, about that beer I owed ya!", a direct nod to the original saying.


 * Continually using the microwave oven located on the way to the locker room will cause it to explode. This "microwave casserole" incident is mentioned by Doctor Magnusson in Half-Life 2: Episode Two.


 * In Gordon Freeman's locker can be found several easter eggs: a baby's picture and the books The Orchid Eater and The 37th Mandala, written by the series' writer Marc Laidlaw. Other lockers bear the names of Valve employees, such as Marc Laidlaw, Kelly Bailey, Ted Backman, Chuck Jones, John Guthrie (which is open in Unforeseen Consequences and contains an American flag and ammo for the pistol), Ken Birdwell, etc.


 * In the test chamber, if the sample is pulled from the Spectrometer, one of the Vortigaunts teleporting in there won't teleport out; instead, he stands on the cart and attacks Gordon. He will be there after the map change, floating in the air, therefore it is not advised to remove the sample.


 * According to the Half-Life instruction manual, the Resonance Cascade begins, and this chapter ends, at 8:58.

Chapter 3: Unforeseen Consequences


"Prepare for unforeseen consequences"

- The G-Man whispers in Eli Vance's ear

As Gordon Freeman's efforts to reach the surface to get help in the aftermath of the Resonance Cascade begin, more problems get in his way. The building is falling apart around him, and mysterious alien creatures are materializing from thin air. Gordon acquires his trademark crowbar to help him get past obstacles, and later he can steal guns and other weapons to aid in his escape.

After being told that all communication outside Black Mesa has been lost, Gordon is requested by his colleague Eli Vance to try to make it to the surface in order to acquire help. Black Mesa has received massive structural damage, and to make matters worse, aliens from the borderworld Xen begin to teleport in around them. Most are reacting to their new surroundings, but even more hostile are the creatures Gordon saw earlier (called Vortigaunts). Gordon occasionally witnesses the man in the suit, the G-Man, watching him from out-of-reach places, always walking off before Gordon can get to him.

Since the tram is too damaged to work, Gordon must cross Sector B's Coolant Reserve Facility in order to find a way out.

Trivia

 * This chapter begins at an unknown amount of time after 8:58. (However, given the fact that "We've got hostiles" is around evening time, there is a good possibility that "Unforeseen Consequences" begins in the afternoon.


 * The original name of this chapter was: The Portal Device.


 * In the "malfunctioning laser hallway", there are two dead security guards while prior to the incident, there was only one guard present.


 * The green and red button on the laptop (the one that is locked to prevent Gordon from using it) from Anomalous Materials is changed to be a large, white button.


 * The door leading to the monorail can be opened after the Resonance Cascade by destroying its monitor (or the controller). Through the door a scientist can be found, who will fall to his death. 9mm ammo can also be found there.


 * The title alludes to the G-Man's words to Eli Vance prior to the Resonance Cascade, where he told him to "prepare for unforeseen consequences". As revealed by Eli to Gordon in Half-Life 2: Episode Two, the G-Man is where he got the alien sample from.


 * In Half-Life: Source, the player may spawn incorrectly at the beginning of the second map instead at the Anti-Mass Spectrometer when the player chooses this chapter in the menu.

Chapter 4: Office Complex


Minutes after the Resonance Cascade, Gordon reaches the office complex, where several scientists are barricaded into their rooms, hiding from the rampant aliens appearing inside the complex. He then hears rumors from these scientists that the military have arrived to rescue the people trapped in the facility.

Trivia

 * The original name of this chapter was: The Office Warrens.
 * This level most likely takes place at opposing force of "Incoming"


 * The Freezer Area can be skipped; before entering it, a security guard can be found. If he is taken to the door on the left of the entrance to the freezer and then pushed into it, he will get stuck in it for a while and the door will open, allowing the player to skip the freezer area. However, player may note the security guard and a zombie behind the door are invisible.


 * Around the "cafeteria" area, there appears to be an "inaccessible" room that contains a health station, grenades, and ammunition. The only way to enter inside is to use a vent opening (located behind a door where the aforementioned security guard is found). Through this pathway, several headcrabs are present.

Chapter 5: "We've Got Hostiles"
"We've got hostiles!"

- HECU Marine

This chapter finds Gordon Freeman making good progress, passing through various storage and staging areas, continuing his hunt for a way to the surface. Gordon learns that the soldiers rumored to be coming on a rescue mission have already arrived. He attempts to join up with them, but walks into a room to witness a Marine killing a scientist. It is then that he discovers that the Hazardous Environment Combat Unit, which has taken control of Black Mesa, is not just killing the aliens, they are also targeting everyone connected to the project, including himself.

When he eventually reaches the surface, Gordon finds himself in an area totally under the control of the military and, worse, in the middle of an artillery bombardment - taking cover, he is forced back into the underground complex. However, it is revealed that the surviving members of the Lambda Team (in the Lambda Complex at the other end of the facility) may be able to close the dimensional rift. Therefore, Gordon begins the journey across Black Mesa to reach them.

Trivia

 * The original name of this chapter was: The Security Complex.


 * In the beginning of the chapter, a scientist is seen screaming about opening the silo doors. You can talk to him while he's waving his arm (timing is important),then lead him towards the office door and push him into it to make it open. Then, the player must kill the scientist, so the door immediately reopens after closing, as it detects an entity (scientist's fresh corpse) blocking its way. In the office, you can press the button to open the silo door, and continue to Blast Pit, skipping the whole chapter.


 * In Half-Life (but not Half-Life: Day One) it is shown that this chapter plays through the sunset, which, in New Mexico, occurs at 4:58 PM.


 * In Half-Life: Day One, the Valve theme song was supposed to play when Gordon picks up the MP5.

Chapter 6: Blast Pit


Gordon Freeman enters an abandoned, largely sealed-off area of Black Mesa dating back to its earlier days as a missile complex, full of mothballed machinery and now used as a dumping ground for toxic waste from the rest of the facility, where the HECU soldiers have yet to get a good foothold because of the high concentration of aliens in the area. It is here that Gordon faces a deadly new foe, the Tentacle. However, after reactivating the fuel, power, and oxygen lines, Gordon is able to kill the Tentacle by using the rocket engine at the top of the silo that the Tentacles were inhabiting, and finds a way out through the meters-long dirt tunnel dug by the Tentacle.

Trivia

 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file was: Screams and whispers.


 * The Scientist taken by the Tentacle can be saved; by running to the scientist and talking to him as soon he begins to run. The scientist will talk without being taken by the Tentacle. The Tentacle will do its scripted movement.


 * In one part of the chapter, Gordon needs to get in the vent at the ceiling high above him. He does this by turning on the fan, which makes its blades start to constantly move. After this, he jumps in the moving air above the fan. While this "flying" is possible in the real world it should be noted that the wooden planks near the vent, fall straight down, which is in contradiction to Gordon's state.


 * After killing the tentacles and going down the tunnel, if the player is to return (by means of noclipping) then the tentacles will reappear as they weren't killed. This may not happen in the Steam version.


 * When the player gets to a large pool of waste, with two Bullsquids roaming in it, there is a shelf with health and battery that seems to be unaccessible. The player can (quickly) travel across a steep part of the wall, and collect the goods.

Chapter 7: Power Up


Trying to reach the surface once more, Gordon's progress is thwarted by a clash between a Gargantua and HECU soldiers in the Sector E Materials Transport. He then learns from a dying security guard that if he restores the generator, he can ride the monorail to the surface. Freeman enters the Houndeye-infested subterranean areas and activates the generator, restoring power to the vicinity. After activating more switches, he destroys the Gargantua patrolling the area by turning on the huge transformers supplying power to the tram line.

Hitching a ride, he smashes through a barricade of concrete blocks before continuing on his way.

Trivia

 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file was: Footfall.
 * If the player attacks the dying security guard, he'll say the lines that the others do when attacked, but stay lying down. In Source version, the guard will die if attacked.
 * If the player kills the gargantua with conventional weaponry before restoring power, its sonic roars will still be heard throughout the level and will cause parts of ceiling to collapse.
 * The entire level can be skipped by proceeding to the railway barricade, then using tripmines as steps to climb over the barricade.

Chapter 8: On A Rail


As Gordon Freeman rides a monorail in the Materials Transport section of Black Mesa, he learns from a security guard that he must ride to the High Altitude Launch Center to launch a satellite, which the Lambda Team can use to reverse the effects of the Resonance Cascade. He also discovers the HECU's true hatred for him, as well as larger reinforcements: sandbag bunkers with rapid-fire sniper rifles, mounted machine gun turrets (manual and automated), and even mounted rocket launchers. After going round in circles, it seems, for a while, he goes up several elevators and at last reaches the surface again. At the launch site, he sends the rocket up into orbit, and regretfully goes back below ground.

Trivia

 * If the player presses the rocket launch button through the wall, he can witness the rocket launching without being sealed off in the launch room. It reveals that the rocket clips through closed silo doors, and also disappears entirely shortly after being launched.
 * In terms of number of maps, On A Rail is the joint-largest chapter of Half-Life, consisting of 10 maps. The only other chapter to equal this is Surface Tension.
 * The moon can not be full, as there were no full moons on all of the May 16s in the decade that Half-Life takes place in.

Chapter 9: Apprehension
Continuing towards the surface, Gordon encounters a terrifying new aquatic creature, the Ichthyosaur, and acquires a deadly new weapon to fight it. After an underwater battle with the creature, he manages to escape and get back on his way.

After battling with the Black Ops, another "rescue" crew trying to kill even the HECU, Freeman is captured by the HECU. They remove all of his weapons, and leave him for dead in a trash compactor. Thankfully, Freeman escapes once again, making his way back into the battle.

Trivia

 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file was: Abandoned silo.
 * The player can skip battling the Ichthyosaur by allowing himself to be caught by the barnacle closest to the door exiting the area, then killing the barnacle while moving forwards.
 * After killing the Ichthyosaur, and going down stairs, the player can see a box with shotgun ammo. If the player goes for the ammo, the top of the box will break, and a Vortigaunt will spawn. This won't happen if the player ignore that ammo.
 * The knocking out of Gordon Freeman must occur after 6:08 AM, as that is the time of New Mexico's sunrise.

Chapter 10: Residue Processing


After escaping from the trash compactor and getting back to the surface, Gordon stumbles towards a mostly abandoned part of the facility, meant for processing and disposing of waste and hazardous materials. Dodging and jumping through antiquated compaction machines, great vats of green waste, and slipping through furnaces, as well as riding on gravity-defying conveyor belts, Freeman escapes to a hidden part of the facility.

Trivia

 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file, was Chutes and Ladders.
 * The security guard who was shooting at three headcrabs can be saved, provided that the player is fast enough. As the guard is distracted, run to the hallway next to him and kill the barnacles. The guard will do his scripted sequence but afterwards, he won't die and he can be interacted to follow you.
 * It is possible to drive the walls that attempted to smash you.

Chapter 11: Questionable Ethics


After escaping, Gordon eventually winds up in a secret part of the facility where he discovers that scientists had been "collecting" specimens from Xen long before this whole mess occurred. In it, Gordon Freeman continues to rearm himself against the HECU, and rejoins the battle against these enemies. Gordon also encounters the alien military units, the Alien Grunts, and he finds one of the most powerful weapons in the Half-Life universe, the Tau Cannon, after a security guard accidentally blows himself, a scientist, and a barricade up by overcharging it. Soon, he heads outside to search for the Lambda Complex.

Trivia

 * The whole laser-activating sequence can be skipped if the player opens the door leading to four scientists by pushing a button that's supposed to open it through the wall. This cannot be done in Half-Life: Source.
 * There are unused Scientist quotes that were most likely meant to be used in this level. Apparently, either Gordon or an NPC was to confront a scientist and demand why were they keeping Xen specimens. The scientist was to respond "Nature MADE them, we were only studying them!"

Chapter 12: Surface Tension


After arming himself with advanced prototype weaponry, Gordon again reaches the surface. It has become a war zone. The Vortigaunts, along with Alien Grunts and Gargantuas, have begun making determined attacks against the Marines, and the tide of the battle is beginning to turn in favor of the aliens. The Marines call in reinforcements, but it isn't enough. Gordon must scale cliffs and navigate the bombed out buildings while avoiding both sides as the forces of Xen begin to dominate the battlefield. Finally, Gordon reaches relative safety underground.

Trivia

 * The original name of this chapter, Cliff Hanger, was used on E3 1998.


 * Like "Half-Life", "Blue Shift", "Opposing Force" and "Decay", "Surface Tension" is a scientific pun, referring to the properties of water which makes certain objects float above it.


 * A part of a map in this chapter was used to create the map Hunted in Team Fortress Classic.


 * The canyon scene was mirrored at the end of the Half-Life 2 chapter Sandtraps, the Headcrab in the last pipe being replaced by a Fast Zombie. The Apache scene is also mirrored at the end of Lost Coast.


 * The Chopper which hunts the player down some point of the chapter can be destroyed using a fully charged Tau Cannon.


 * The player can make the Chopper destroy itself by letting it see you when it first arrives in the map, firing rockets at you, and the rocks (which kill the Chopper as it is in the explosion radius).


 * This chapter takes place at the same time as the Half-Life: Opposing Force chapter "We Are Pulling Out".


 * There are actually 3 different helicopters in this chapter. One appears at the dam, the second one at the minefield, and the third one right after the player acquires the rocket launcher. Therefore, it will always appear in those sections regardless of whether the player destroyed it earlier or not.


 * A big part of this chapter can be skipped if the player jumps from the first set of fences before the dam passage to the rocks at the bottom. There will be a dead scientist on the target rock and if the player slowly slides on the edge of the canyon he can reach the rock or just beside it, in an area where you have to crouch to move.


 * There is an area where a lone Tentacle is residing. In that area, the player can obtain ammunition. Moreover, there is a "secret" entrance that leads Gordon to the minefield (where the entrance to the sewers is located).


 * In the cliff scene (where the player can acquire the RPG), the player does not have to slide down the pipes. Instead, at the area where Gordon exits out of the sewers, the player can jump down and find a crushed HECU marine with some health-kits and a 9mm clip. Then, the player can progress further down and reach the lone battery.

Chapter 13: "Forget About Freeman!"
"Forget about Freeman! We're abandoning the base! If you have any last bomb targets, mark them on the Tactical Map, otherwise, get the hell out of there!"

- HECU commander

In this chapter, the HECU determine that they're fighting a losing battle against the Xen aliens and, having continually failed to neutralize Freeman, abandon their mission and begin to evacuate the facility, calling in air strikes and heavy artillery to cover their retreat. Meanwhile, Gordon makes his way into an underground storage garage to avoid the bombardments, and eventually fights his way through scores of aliens and several groups of the decimated HECU forces before reaching the Lambda Complex.

The Marines begin to evacuate Black Mesa and air strikes begin. Gordon navigates underground water channels and tries to avoid scores of alien invaders as they pick off remaining Marine stragglers.

Trivia

 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file was: "You're on your own".
 * HECU officer, radio operator that gives the orders to Cooper, near the end of the previous chapter Surface Tension says following text: "Come in, Cooper! Do you copy? Forget about Freeman! We're abandoning the base! If you have any last bomb targets, mark them on the Tactical Map! Otherwise, get the hell outta there! Repeat: we are pulling out and commencing air strikes! Give us targets or get below!". From sentence in the text comes the name of the eponymous chapter.
 * In Half-Life:Opposing Force, this event is mentioned again, however, Adrian Shephard was at the military checkpoint when the HECU officer transmitted the message at the radio, making a focal point of the two games.
 * The chapter name is mentioned again in another, more frantic radio transmission. This transmission seems to have been to all troops, and is as follows: "Forget about Freeman! We are cutting our losses and pulling out! Anyone left down there now is on his own. Repeat; if you weren't already, you are now- *transmission is lost*"
 * By Noclipping through the Elevator in c3a1, The elevator is intact, and if the player moves around, it makes the map change, but crashes the game as the map pointer where the Elevator leads to no longer exists.


 * In the map file, viewing it in the Hammer Editor shows that the elevator had a "target" attribute, and the value was c3a1ele - a nonexistant map file. So it's possible that this elevator may have been part of a map that was cut from the game.

Chapter 14: Lambda Core


In this chapter, Gordon arrives at the Lambda Complex, where he believed the science team to be sheltering from the Xenians, only to find that the majority of the complex is now overrun by hostile creatures. He is informed that he must flood the reactor chambers in order to access the core, and that a team of scientists is waiting for him at the tip of the reactor. Gordon must then navigate through the Lambda Core, facing numerous assaults from the Xen forces (the primary enemy, now that the HECU has pulled out). In the end, he learns that a single large entity is hosting the invasion, and that he must teleport to Xen to stop it.

After much struggle, Gordon finally reaches the Lambda Complex, where he discovers that the Lambda Complex is where they developed the teleportation technology that allowed scientists to travel to Xen in the first place. The handful of surviving personnel, who have held themselves up in a small stronghold, inform Gordon that, unfortunately, the satellite he launched was not able to reverse the effects of the Resonance Cascade because an immensely powerful being on the other side is keeping the portal between the worlds open, and Gordon must kill it to prevent the Xen aliens from taking over completely. But before being teleported to Xen, Gordon gains access to several ammunition, health and HEV-charge caches, the Gluon Gun, and he is finally reunited with the Long Jump Module (not seen since the Hazard Course). After an attempted interception by Alien Controllers, the scientists activate the teleporter and Gordon is teleported to Xen.

Trivia

 * The scene near the end of the chapter with the scientist holding the shotgun was mirrored near the end of the Half-Life 2 chapter Entanglement, where Dr. Kleiner was holding a Shotgun as Alyx and Gordon arrived in the teleporter.


 * The Gluon Gun can be found earlier in the level guarded by a lonely scientist.
 * The old level name featured on Half-Life: Day One, given in the "titles.txt" file was: Down and out.
 * It is possible to skip the entire portal-opening sequence by climbing onto the curved concrete structures and falling into the portal just after forcing any entity into it, for example a snark or shot hivehand hornet. This is because any entity can trigger the instant death script, and the player bypasses it because, weirdly, it needs a brief period of time to "recharge".

Chapter 15: Xen


Gordon Freeman arrives in the borderworld of Xen.

On the strange borderworld, Gordon encounters many of the aliens that had been teleported into Black Mesa in their natural habitats, as well as the remains of some HEV-wearing researchers who came before him. In order to progress, he needs to re-activate a portal inside one of the islands in order to venture more of Xen's perimeters.

Trivia

 * Xen is the first chapter in Half-Life to consist of only a single map. The only other chapters to share this trait are the final pair, Nihilanth and Endgame.

Chapter 16: Gonarch's Lair


Freeman is made to face one of the Nihilanth's most powerful minions: the Gonarch in her lair.

Trivia

 * It is possible that Gonarch's Lair was originally placed after Interloper because Gonarch's Lair map names start from c4a2, while Interloper map names start from c4a1a.

Chapter 17: Interloper
Gordon's journey across Xen continues, but his supplies are running short, spent on destroying the Gonarch. He also comes across the Xen army's Alien Grunt cloning facility, where the army is created. It can be noted that the Vortigaunts in one of the factories are not hostile towards the player, and will ignore him unless attacked. The final map of this level takes place in a pitch-black void with floating rocks and an ominous-looking red portal at the end.

Trivia

 * If a non-aggressive vortigaunt is attacked and there is a healing shower nearby, it will immediately go inside to heal itself, and attack the player shortly after (not to be confused with a scripted sequence where the vortigaunt disappears upon entering the shower).
 * It is interesting to note that at the portal to the game's last battle, the voices of scientists that Gordon has previously encountered throughout the game, including some not even heard at that time, such as the voice of a scientist: "Get him out of there! Shut down the equipment and someone get him out!", can be faintly heard, although hard to hear in-game through the alien sound effect around it, with no proper explanation as to why. Note that the altar looks like a warped version of the Anti-Mass Spectrometer chamber.

Chapter 18: Nihilanth
"Win, you cannot win."

- The Nihilanth taunts Gordon

In a vast cave, Gordon finally confronts the powerful and mysterious being that is holding the portal open. Gordon destroys the Nihilanth's shield, allowing him to destroy its vulnerable brain. As the creature dies, it floats toward the ceiling, and explodes in a giant green blast that overpowers Gordon's senses.

Trivia

 * If you save in the area directly before entering Nihilianth's chamber, it says you saved on Xen, even though this is the end of Interloper.
 * If the player dies after finishing off the Nihilanth and doesn't reload the game, he will still be teleported to the Endgame chapter and able to finish the game, albeit only the bad ending is possible, since the player cannot move.
 * In the area where the player encounters the Ichthyosaur, there is a scientist by himself in a hard to reach area. He can be interacted with but he has no lines.

Endgame


"Time to choose!"

- The G-Man

When Gordon comes to, he is confronted by the G-Man. Both are transported to various locales around Xen, while the G-Man praises Gordon's actions in the borderworld (which he refers to as "a nasty piece of work"). He explains that his "employers", agreeing that Gordon has "limitless potential", have authorized him to offer Freeman a job. The final teleportation takes Gordon to the same tramcar that he rode on at the beginning of the game, but apparently flying through space at immense speed. Gordon accepts this offer by stepping though a portal, and, finding himself floating in nothingness, hears the G-Man's voice one last time: "Wisely done, Mr. Freeman, I will see you up ahead..." The story continues from this point in Half-Life 2.

Alternatively, the player may choose not to step into the portal in the final scene. This causes the unarmed Gordon to be teleported into a giant cave facing rows of Alien Grunts and Manta Rays as the game ends with the G-Man's comment, "Well, it looks like we won't be working together. No regrets, Mr. Freeman." Gordon's appearance in Half-Life 2 suggests that this ending is non-canonical. Following this scene is a status report saying, "Subject: Freeman; Status: Observation terminated; Post Mortem: Subject declined offer of employment."

Trivia

 * The chapter name "Endgame" is given in the "titles.txt" file and in Half-Life save and load dialogs.
 * The rows of Alien Grunts in the non-canon ending are not all NPC's, if the player noclips out of the barrier, they will see Alien Grunts in sprite form.
 * Even though the G-Man seemingly lets Gordon preserve his suit, he will awaken without one in Half-Life 2.
 * The scene with defeated HECUs was most likely supposed to be shown to Gordon on Earth, but since GoldSrc lacks the ability to change the skybox within a single map, it remained on Xen.
 * During the ending of Half-Life 2, G-Man references the ending sequence, mentioning that he has chosen for you rather than offering you "the illusion of free choice".