The Game starts at "Black Mesa Inbound", and that chapter is one of the more passive ones, so if Gordon's not interested at looking at the scenery, he can change the level to c1a0 to skip to the first "real" chapter. There are some notes connecting to its expansions however:

1. The security guard knocking on the door at the beginning is the actual Barney Calhoun, whom the player plays as in the game "Blue Shift".

2. Most of the area is "revisited" by Barney Miller in the game "Azure Sheep".

3. The G-man can be found near the end of the chapter. This man will follow Gordon throughout most of Black Mesa. Regardless, he is NOT the administrator, Dr. Wallace Breen is. Also, the place where he first appears is also an area "revisited" by Adrian Shepard, a soldier in "Opposing Force".

The true first chapter, all that's needed is to get the H.E.V suit and go to the test chamber. There are some fun things to do here as well.

Gordon is late. He goes to the lobby and the guard there says that he needs to get his H.E.V suit and to then hurry down to the test chamber. Towards the Research Labs, he can also spot the G-man arguing with a scientist. Before entering the locker room, Gordon can check out the room to his right. A pair of Scientists are eating lunch, and Gordon can mess around with the microwave! The locker room holds the suit, and Gordon can also grab a battery from his locker. He then must follow the blue line on the wall towards the Development Labs. The guard will let him in only if Gordon has his suit. Gordon then goes down the elevator (or down the ladder, which is quicker), and then runs through the hallways leading to the test chamber. In the middle of the jog, he meets 3 of his colleauges telling him that they are taking advantage of the situation that they currently have and that Dr. Breen, the administrator, had gone through a lot of work getting the crystal sample, and is demanding to get some sort of analysis for his efforts.

One of the scientists open the door for Gordon to get through and in the next room, Dr. Eli Vance and his colleague try to fix some equipment that has gone wacko. Down the elevator and through the hallway, two more scientists argue about the dangers of a disaster. After the conversation, they open the door for Gordon to get through. Later, Gordon is asked to turn on the switch above at the catwalk. Once he does, the other workers activate the working sequence. Once they announce that the sample has arrived, Gordon must push the crystal carrier into the Portal. Unfortunately, disaster strikes and Gordon must watch something unnatural unfold.

No matter what Gordon can do, he still causes a resonance cascade. Aliens are everywhere, and many human casualties are occurring!

When Gordon regains consciousness, he must retrace his steps. When he backtracks, he'll meet Dr. Vance and his colleague in great worry. Dr. Vance tells Gordon that he needs to get up to the surface and send help. He then opens the door to let Gordon through. He must then keep going, dodging any obstacles in the way, and during so, he'll get a crowbar. Smash his way through the door and into the elevator to the elevator, where it has malfunctioned, killing the scientists inside. Down where the screwed-up transport had landed is a battery. Up at the top level is a guard shooting some zombies. When Gordon approaches him, he is relieved to see Gordon alive and is wondering what he killed. Gordon should then ask the guard for his help and then retrace his steps once again. Along the way, the two will encounter two more zombies. Gordon can deal with them himself, or let his companion kill them. Once they have been dispatched, the two will come across two familiar hallways. The lockers in the locker room have 9mm ammo and a battery, and also has a first-aid station. The hallway leading to the lobby is the way to proceed to the next area. But first, Gordon should go to the tram entry, where a scientist soon grabs on a rope for his life, and falls. There’s a round of 9mm ammo there.

Gordon should go through the tiny hole where some electrical equipment falls onto headcrabs (and could possibly kill Gordon if he isn't careful). Some of the equipment are laid down for Gordon to go through another hole. In a nearby room, a scientist is dealing with a headcrab. He kills it, but then he is defeated by another. Gordon then learns the origin of the zombies. Speaking of zombies, one on a chair has gone crazy in the other room. Gordon can kill it. Gordon proceeds through the hallway, where he sees a guard that has killed a zombie who has also been killed by it. Grab his pistol and take advantage of the first-aid station, then go through the doors.

Gordon opens the door and finds a scientist under attack by some houndeyes. Slaughter them all and get the scientist to follow Gordon. When Gordon continues through the hallways, the G-man watches him on a catwalk. If Gordon shoots him, he will be unharmed, but will leave early. More houndeyes will come attack the bumbling scientist in the H.E.V suit. Kill them. There’s another first-aid station in where one of the houndeyes came from. Behind one of the doors in the walls is another headcrab and a passage to some decent supplies. Gordon should climb the ladder and shoot the barrels, massacring the headcrabs and the zombie. To the right, a scientist is willing to open a door for Gordon. He can lead the scientist to an armory, where a dead end and a zombie lies. The question is this: If this is a dead-end, then where is the G-man? Anyhow, kill the lone mutant and the civilian will open the door for Gordon, where some 9mm ammunition, some grenades, and a first-aid station is. Back at the lower areas, Gordon continues to walk through the hallways, where a headcrab is attempting to attack a scientist in a dumpster. Kill the headcrab and Gordon will hear a door get destroyed. The first Vortiguant decides to attack Gordon. After the Vortiguant dies, there’s some ammo where it spawned from. There's a sewer hole. Inside is a headcrab. Gordon can kill it. Also, on the other side of the fencing, a zombie climbs up from the other manhole. Gordon should kill it while it's climbing up. After the kill, Gordon should jump into the sewers, turn the wheel inside, and swim up to the other manhole.

When Gordon goes across the hallway, he will see a giant platform. On the upper tier, there's a switch next to the dead security guard. Activate it and go onto the platform. The platform will go down, and headcrabs will begin to fall above. For a quicker way to deal with this, Gordon can jump onto the slope on the right and slide down unharmed. There’s a first-aid station here, as well as some boxes on the other side. Throw some grenades at the boxes. To get to the other side, Gordon can walk on the ridge near the wall. A houndeye spawns here. After killing it and getting some 9mm bullets, Gordon will come across a bridge which gets destroyed by a bullsquid. The bullsquid then falls to its death. Gordon must climb along the pipes and into the vent. Go to the far side of the vent, grab the batteries, and then shoot the barnacles hanging from the ceilings of the huge room with the canal while the bullsquid is killing the headcrabs below. When it's done, Gordon should kill it and any remaining headcrabs that the bullsquid hasn't killed. He can jump safely into the canal river, making sure that he doesn't get grinded in the generator. To the left is access to the other side of the canal. When he goes through the door, he gets to another giant room, this time with hanging boxes. Climb up and navigate from box-to-box to get to the other side. Simply go through the hallways and proceed through the elevator, towards the next chapter.

This is a chapter that takes place at a more "civilized" area, where there’s tables, rugs, and such. Gordon will also meet a lot of friendly people here.

To the right of the elevator exit, there's headcrabs being massacred by an electric wire. The wire will also electrocute anything else, including protagonists in H.E.V suits. Go inside the vent, and to the left, throw a grenade inside where the fan is. Return to the right, and break the vent door. A scientist nearby is getting eaten by a barnacle. Shoot it and the other two in the room. The other scientist at the table, says that most of the science team is heading for the surface, but he plans to stay here and wait for some rescuers. Inside the room is a door (not leading to where Gordon started), which has a switch that will turn off the power in the area. Now that the power is off, the wire is no longer a threat. Before Gordon goes to the next area, he can go back into the vent and get the ammo where the fan was. Now go through the window and keep going onto the hallway, breaking all the boxes.

A shotgun is in this room. Collect it and shoot the zombie that's about to ambush the guard on the other side of the door. He will then unlock it for him to a room with a headcrab, some ammo, and some health kits. Tell the guard to follow and go back to the nearest area with the double-doors. Behind the wooden door is a zombie that trashes the tiny room inside. DO NOT kill it until it breaks the door open. After killing it, collect the ammo inside and go to the flooded room with a hanging scientist. Tell the guard to hold position and go into the flooded room. Note that Gordon can shoot the hanging scientist. He must go from table-to-table without touching the water to a switch that will turn off the electricity in the room. Gordon can break open the vent and shoot more headcrabs inside. Climb in and duck, making sure that Gordon's head isn't severed off by the fan. On the other side of the vent, Gordon will fall through the ceiling. Open the door in front of him to let the guard through. Behind are some crates and headcrabs that fall through the ceiling. Kill them and set up the boxes to let Gordon climb up them and onto the ladder above. After crouching through the vent, a ceiling turret will activate and will shoot the scientist and unless Gordon is quick enough to reach the switch beneath the turret, will kill him. After deactivating the gun, go through the door, nabbing the ammo, and unlock the other door to let the guard through. Travel to the hallway where the turret was, and throw a grenade at the headcrabs. Proceed up the stairs.

On the top level, another security guard is firing at more headcrabs! Have him follow Gordon and proceed an office area that vortiguants have infested. Go to the room on the left and collect the med kit and battery, watching the scientists fall through the vent. Proceed through the hallway and blast any vortiguants with the shotgun. Left goes to more aliens, and more rooms. Explore the area, and then go to yet another hallway with another pair of vortiguants. At the end (after shooting the barnacle), there’s a room with a scientist. He says that he doesn't want to go to the surface, due to what they did in Black Mesa. Return to the opposite side of the complex and fight the vortiguants hiding behind the vending machines and the hallway. There's another scientist who tells Gordon that he found out that soldiers are on their way to rescue the science team. Up another staircase is a turret on the other side, where Gordon should take out right away with grenades and his Glock. Another method of dispatching it is to go into one of the rooms, smash the ceiling, and deactivate the power next to the turret. Also, some headcrabs, a zombie, and a pair of vortiguants are at the hallways.

Anybody that is currently following Gordon will refuse to continue, due to a hidden headcrab on the vent. Take it out in order for Gordon's allies to advance. Additionally, another security guard is waiting. Apparently, the military rumor has been quickly spread. Down the ramp is a bullsquid and an ammo depot. Yet another pair of vortiguants spawn in the room. After taking them out, Gordon should go through the vent near the door he came in and make his way through the vents to a room with a cache of ammo and grenades. He should then run back to the guard and then throw all of his grenades at the cafeteria with all the zombies and headcrabs. The two proceed to the kitchen, infested by Xen wildlife.

The first area contains two zombies, the other is a room filled with corridors, bullsquids, and headcrabs. In some areas are some ammo, in a corridor, there's a switch that will activate a moving platform above. From where Gordon started, he must climb up the ladder, and move through the counters to the moving platform, destroy the boxes on the platform, and move to the other side. When Gordon is through the first vent, he will come across a vent complex infested by barnacles. Kill them all, collecting their bounty, and jump to the upper vent. There's a headcrab or two inside the vents, just to let Gordon know.

Gordon goes to the other side of a door in the cafeteria. Here, a security guard fails to recover another. Meanwhile, a zombie chases a frantic scientist. Annihilate the hybrid and let the security guard know that Gordon needs his help. Up the stairs is a headcrab. On the other side of a locked door, the G-man observes Gordon, and then walks to another room. At the wide corridor, a zombie falls from a top hallway and another zombie breaks out of a wall. A scientist escapes a room and runs away from the scene. Take the two freaks out, and collect the ammunition in the rooms. The guard says that the elevators are out of order, but that everyone can still climb. That's what Gordon needs to do to get to the next chapter. Jump across the elevator shaft, and climb up to the elevator. A scientist looses his grip on the elevator, but Gordon can still make it up there. Then he goes inside the elevator (breaking the panel) and goes out.

This is the first chapter that features the military. Gordon should not expect the marines to be kind with his company. Watch out! They're very smart!

Shoot the tripmine ahead. The scientist bangs on the window trying to get the security guard to open the silo door, informing what Gordon needs to do. The unfortunate soul gets perished by a zombie from a vent. The scientist goes crazy and runs to the hallway, and gets killed by a turret. Gordon should charge up his suit and his health, and continue. In the next room, he must throw a grenade at the turret. He can then blow up the explosives box and nab the soldier's weapon (MP5/M16). He should then shoot the door's panel to close the door, and escape, evading the tripmines.

The next area spawns a vortiguant slave. After killing it, Gordon comes across two turrets. Taking one out with explosive barrels and killing the slave that spawns behind with another pair of barrels, Gordon can now climb up the crates and escape the scene, closing the fire door behind, and ignoring the turrets.

In the next area, two scientists are about to get attacked by another pair of turrets. Destroy them, and the tripmines ahead. The G-man again watches Gordon from a catwalk, and walks to the right. Gordon climbs up to the catwalks (checking the boxes for provisions) and sees a marine waiting for a scientist.

The bad thing is, the marine becomes hostile to the scientist and kills him (unless Gordon is smart enough to kill the soldier first). Grabbing the 9mm ammo on the table, he goes up the elevator. Another scientist runs foolishly towards a whole squad of troopers! After killing them and using the charging stations, he goes to a pair of catwalks with many barnacles! I don't need to tell everybody what should happen next. Going right, and then running against the conveyor belt, he comes across a supply area with two charging stations, and plenty of ammo. Climbing up to the next conveyor belt, Gordon encounters another marine above some turrets. Dispatch him, and then the turret on the right of the marine's position (below). Then target the tripmine and rush through the door. Two more scientists rush towards another squad of American infantry. Dispatching them all, and collecting the ammo, Gordon runs up the stairs, across the catwalk, and he should then throw some grenades at the grunts below. Also, Gordon may feel free to take out the barnacles over the conveyor belt. He then grabs the supplies he needs (a battery is in a box) and goes up the elevator.

The next area is highly dangerous, mainly because of the osprey helicopter, and the airstrikes. Gordon MUST rush into the nearby bunker and down the ladder, ignoring any marines that try to assassinate him. At the bottom of the ladder, there is some boxes that contain a wealth of 9mm ammo and a pair of charging stations. Gordon should then hurry downward to the wide vent. A fan is in the middle of the vent junction. At the nearest gap in the left vent is some shotgun shells and two turrets. A junction is in the vent after the gap. The right shows a headcrab. The path on the right leads to some 9mm ammo and two soldiers complaining on their mission. It seems that the soldiers' mission is to eliminate any witnesses on the project. The other path leads to a room with some supplies and vortiguants that spawn on the other side. The vent beneath the fan (at the junction) leads to more shotgun shells. Make sure that Gordon crouches under the fan. At the bottom, there's a vent leading to another vent that gets Gordon to the silo controls. There, a nearby scientist informs Gordon that he must get to the Lambda team to stop the madness. But to get there, he must get through the silo complex, and worm his way in an archaic rail system (as the transit system is out of order). Gordon should open the silo door and charge his health and armor at the power stations before he goes through.

This is one of my least favourite chapters that don't take place on Xen. Also, Gordon should conserve his ammo here, because there are hardly any ammo depots. There's a tentacle trio that Gordon needs to get past. He must find out a way to destroy it.

Gordon must hack his way through the barricade and kill any headcrabs and the bullsquid. There's a control tower with a switch to activate an elevator. A zombie bashes through the door next to it. Inside the room it came from is a pack of grenades. When the elevator comes up, Gordon must then go down an onto the train (this is NOT the old rails the scientist was talking about). Avoiding the aliens nearby, Gordon eventually gets launched up into the air. He should try to land on the nearest crate. Kill the bullsquid ahead, and make his way across the boxes on the toxic waste to the other side. Into the pipes he goes.

He then should kill the two bullsquids and jump across the pipes and onto the platform. Collect the supplies, run across the pipes and onto the elevator. Some houndeyes attack Gordon. Shoot them all. Also, shoot the barrels on the bridge and the headcrabs on the other side. Walk across the small pipes to the door into the silo. A zombie comes in after Gordon opens the other door. Blast it with the shotgun. He then comes across a dying scientist whose last words tell Gordon how to destroy the tentacle creature ahead (using a rocket engine). Another scientist in the control room attempts to activate the engine, but one of the tentacles grab him into the dangerous field. According to the controls, Gordon will need to unlock the fuel & oxygen pipes, as well as to turn on the power. Kill the barnacle near the ladder, climb up it, and a security guard will tell Gordon that the Tentacles do not see, but hear, and they have very, VERY sensitive hearing. Gordon can either distract the "outer space octopus" with grenades, or walk across the walls to get to the two areas. Either way, he should destroy the barricades with grenades.

The first airlock Gordon comes across leads to the fuel & oxygen pipes. There's a manhole leading to a sewage system. But first, there are two zombies in the way. Climb down, go left, and climb up the ladder. Another zombie is here. Grab the grenades and then shoot the two zombies on the other side of the door. Climb down to the bottom area and turn on the switch. Now quickly climb back up and then jump onto the fan's covering area. It will make Gordon levitate to the top, where he needs to smash another huge barricade. Gordon must make his way through the vents and then when he reaches the fuel & oxygen controls, he must deal with some zombies and a headcrab. He can then backtrack to the tentacles area. Gordon should then go to the bottom. Save the grenades though, he'll need it later.

The next area leads to the power generators. First off, some houndeyes rush towards Gordon's position. After killing the herd, he must turn a bullsquid and a few barnacles into a bloodbath. Before he proceeds, he should push a metal crate to a bigger crate so Gordon can walk across the pipes next to the wall (the reason is explained later). Activate the elevator, but don't ride on it, as it will drop Gordon into a tub of anthrax. Instead, he should climb down the ladder. When he's down, a scientist near the electric generator says that he sent his colleague, Smithers, to turn on the power, but he never appeared again. Gordon should walk on the huge pipe across the waste and kill the zombie. He can use the moving platform (a bullsquid is below) to get to the upper levels. Avoid the moving platforms. On top of the silo core, Smithers refuses to move until the disaster is over. Turn on both switches on both sides to turn on the electricity, trapping the coward on the generator for eternity. Return back to his colleague, who has announced that the power is on and the engine will be running. Climb up the ladder, and at the top, land on the elevator's roof. Here, since the power is online, Gordon will need to climb up the boxes and onto the wire on the wall to get past the electrocuted water.

Return back to the tentacle-infested silo and quickly return to the top tier. There, Gordon must turn on the rocket engine, burning the tentacles so Gordon can get past. He can then go to where the tentacles last remained and climb down the tunnel. Above at the pool, where what remains of the mostrocity lays is a revolver with its .357 ammo. Keep swimming down and at one of its edges has an opening to some stations and some pipes to the next area. Run across the pipes, switching from one to another to a rather large one with a wheel. Turn it and Gordon should be able to get to the other side. At some time, the pipe will collapse and Gordon must land on the table. It's a long fall, but he will be healed by the med kits on the table, squishing the headcrab. The boxes contain lots of useless tripmines, so only look for the health kits and ammo. Gordon may run to the next chapter.

Back to the marines, Gordon will need to retrace his steps often here. He needs to turn on the train power and the track power.

The G-man is on the control terminal, watching Gordon. Meanwhile, a Gargantua is massacring two marines. Use this as a distraction and run to the hallway across the other side. A vortiguant slave runs toward him, but he can take it out with the barrels. To the left, there's a fuel leak. After that, more vortiguants ambush Gordon. The bridge collapses. Gordon should check the boxes for supplies and kill the headcrabs that run away. Destroy the barricade and go through the door to find a wounded security guard. He tells Gordon to turn on the power and warns him that there's many enemies between them and the generator room. There's many helpful supplies here and a pair of charging stations. Down the ladder, there's a pack of headcrabs. There are many aliens to deal with to the next area, but Gordon can take them out easily, since there's a lot of barrels for the last batch.

Towards the door to the toxic pit are two upper levels. The first has a soldier getting eaten by a bullsquid. Shoot the bullsquid through the hole and grab the ammunition. The next tier alerts a soldier. When Gordon is on the second level, he should give the marine a clean shot to the head with the revolver. The room above has a turret, another trooper, and some boxes filled with supplies. One of them has a round of bolts for the crossbow, which will be needed later.

The next area has a commando inside a garrison. Shoot the explosive boxes. Collect the stuff and then when Gordon goes up the ramp, another commando alerts his squad at the left balcony. Take him out and massacre the squad of men in the radio room. Make sure the vent doesn't get destroyed, because if the shaft gets open, headcrabs will spawn out of it. Check the zone for ammo, and then return to the radio room and turn on the elevator. First, Gordon should throw a nade in the elevator (there are tripmines at the bottom floor). Then go down, killing any houndeyes on sight, and turn left at the big room. The spiral leads to the generator. Shoot the headcrab ahead and proceed downward. Instead of taking the sucker's way and going directly to the boxes to smash them, shoot the boxes to de-jam the generator. Then return to where the headcrab was and run to the controls. Then detour back to the radio room, killing the squad of soldiers that comes down the elevator. Another squad has returned to the area! Kill the commando and then shoot the boxes up ahead to dispatch the other foes. Return to the control room with the wounded security guard, assassinating any enemies that get in Gordon's way.

The door behind the Gargantua is now open! Make a run for it and go to a room with two enormous electric coils are. Go behind them and turn on the switch. This will annihilate the Gargantua for good. Go back to the main area and make the train go to the turntable. Return to the control room with the guard. He tells Gordon that he can't go with him. Go to the switch and drive the train through a barricade.

From here on, I will classify the marines specifically, since this chapter introduces more types of infantry.

A guard at a rail stop says that Gordon needs to launch a rocket to let the Lambda team know his arrival. The military aborted the launch, so Gordon needs to put the rocket into the skies himself. After his speech, take out all of the barnacles on top of the elevator and ride the train there. Keep riding through the flooded rails onto a dryer area.

I should tell Gordon this: There are these switches on the walls. The purpose of these will turn the train to an alternate path. To turn these, shoot it. They are hard to miss and are mounted on the walls. Gordon must go open a door to get through, but he needs to get all the way across the other side to the controls. Make his way through the rails, killing any aliens and he will eventually come across a rail station where a bullsquid and a headcrab have taken charge. Collect the supplies and smash the boxes and the turret. Backtrack to the area with the door, shoot the switch, and drive on. Note that there are other tracks to go to, leading to supplies, but I avoid those.

Now it's where it gets fun! Before Gordon drives his train to the platform, he can see a commando's pair of legs. Shoot them two times with the revolver and then go up. Another two troopers are on another elevator, so shoot them while the rival elevators go up. At the end of the upwardness, a grenadier is on an unsafe wooden plank. Shoot him in the head and then continue forward. A battle between the soldiers and the vortiguants occur. Sneak past this and drive the train to a stop, with a turret. Kill the trooper next to it and then take the remainder of the squad with the turret. On the side with the dead aliens lead to some headcrabs, the troopers Gordon dealed with at the elevators, and a power station. Gordon can turn on the switch and drive his train to the next place, but he should get off it after he accelerates it and walk to the turret area. On that side is some stairs. Throw some grenades up the stairs and then take the bounty. A trooper is hiding in a room, while some vortiguants ambush a commando. Kill the living things, destroy the tripmines below, and then go to the parcel room, destroying the boxes that aren't on the shelves for some .357 ammo. Go down the stairs and kill the trooper. Destroy the box underneath the stairs and destroy the vent. Crawl underneath and collect the satchels and killing the headcrab, hearing gunshots from above. The vortiguants will most likely win, as the marines above are recruits. Back above, kill any survivors and then man the train (checking the place for supplies) and move on.

There’s some grunts and a commando on the left of the rails. Throw a grenade or two and collect their weapons from their bodies (or what's left of them). Go to the hallway on the right of the rails and sneak past the battle and into the tiny room, breaking the barricade and boxes. The guard nearby will take care of the conflict. When all the enemies are vanquished, there's a room with a battery, a first-aid station, and headcrabs that fall from the ceiling. The next area has some boxes and a turret. Kill the trooper manning it and open the fire doors. Detonate the tripmines and then dispatch the trooper at the bottom tier in the silo. Go down where the marine was and then collect the .357 ammo in the office. Also, there's a hidden H.E.V charging station. Then drive the train. Duck underneath the lasers and shoot the two bullsquids with the revolver. There's a door leading to another bullsquid, some corpses and ammo.

Driving onto the next area, a rocket turret fails to get Gordon. Shoot the tripmine next to its wielder and drive on. Shoot the next tripmine. Voriguants and a first-aid station wait at the next train station. Turn the aliens into corpses and then detonate the tripmines. A few headcrabs wait above the tripmines. One of the crates above the stairs contains a satchel. Also, there's a commando and a grunt guarding a control panel that will open the gates. There's even an armor station next to the panel. Instead of going back to the original train, jump in between the rails and search for a second train. Use it and drive on. If Gordon takes the other train, a trooper will use the "real" train and Gordon will come across a trap. The next area to the right has a turret, and a nasty platoon. Launch a grenade at the turret and clear the area. Then use the switch next to the turret's bunker to open the gate. The next place has an elevator to the right. Break the boxes near the elevator and put the satchels inside the elevator. Gordon should now drive his train and detonate the satchels, watching some gore fly by. Ignore the trooper and then when Gordon's all the way to the top, he can go into the room with boxes and break them. Down a floor via the ladder, he can collect the satchel nearby and toss it down, detonating it when it reaches the bottom. Return to the train and drive past the electricity and detonating the tripmines.

There's an area where crates are being transported throughout. Behind the set of stationary boxes is a grenadier and a commando. Keep driving the train, avoiding the bad guy with the rocket turret (or kill him). Soon, Gordon will come across a switch. Shoot the switch so Gordon won't retrace his steps. He will then come across a hole in the rail. The best way down is the stairs. When the loading starts, he should toss an explosive down, which will set off the tripmines and a turret. Jump across the red laser and take out the zombies in the office. There's also a cache of grenades and a first-aid station inside. Knock down the other three turrets and run across the rail. A bunker turret and a commando are armed to the teeth. Take out the guy manning the turret, then kill the commando. Collect the provisions and move on.

Outside, two soldiers talk about Gordon. After the conversation, launch a grenade at their position. A sniper is also here, on the cliff. Launch another grenade from the automatic weapon at the camo area. The box contains some shotgun shells. Enter the red fire doors. A squad containing a trooper, a grenadier, and a commando are blocking the way to the rocket control station. Take them out with the gun on the opposite side. Enter the rocket bunker and use crates to get up the stairs without detonating the explosives in the area. Another couple of marines complain about their mission. Shoot the both of them and then go to the bunker controls and launch the missile. Return to where Gordon dispatched the marines and enter the newly open door and go down the stairs. Collect the ammo and drive the train towards the next chapter.

Here, some new creatures infest this area, as well as some other obstacles.

The train doesn't stop! Then it goes into the water and crashes! Gordon can skip this paragraph and jump to the water body opposite of the train, but just in case, I'll give the walkthrough for getting to the other side if Gordon stays on the train. Go down to the bottom and break the padlock, allowing the barrels to float to the surface. Go downward and go up the stairs, destroying the zombies along the way, and jump across the bridge of barrels. Then walk along the hallways and into the water.

Swim across the flooded place and then Gordon will come across a ramp leading to the end of the water. There's also ammo in a room along the way, there's a path leading to it, but Gordon must be an active swimmer to get to it. The next room holds an ichthyosaur, which eats a doomed scientist. There are barnacles swarming the area, so kill them. Up the ladder is another scientist, who tells Gordon all about the Ichthyosaur. There's another pair of charging stations here. In the cage is the mighty crossbow. Use it on the Ichthyosaur, dodging its attacks. When it dies, turn the wheel and duck underneath the door.

The next room contains many barnacles. Kill them all and then smash the vortiguants that spawn in the tight area. Collect the shotgun shells and proceed. The next area is also flooded and contains TWO ichthyosaurs! Walk slowly, and jump the damaged area. Then jump into the hole in the mesh and swim down and through. The G-man awaits Gordon as he kills a bullsquid. Another bullsquid spawns after the first. Go up the ladder and go down the stairs leading to a tiny room with some ammo. Go back to the control panels and activate the switch. The pumps will start and Gordon must jump across the pumps without getting squished by the pumps. When Gordon makes it across, a headcrab spawns on the catwalk. When Gordon goes across ahead, a bullsquid spawn behind.

In this area, some terminals, headcrabs, and vortiguant slaves attack Gordon. Take the aliens' lives and charge at the stations. A scientist opens a door for Gordon to get through. He explains that the military is on his tail, and gives a hint of what the next chapter might look like. He then opens the door leading to a freezing area, where Gordon must run through. Shoot any aliens that get in his way and go down the ladder.

This hallway has vortiguant slaves and boxes. When Gordon starts to go across, more slaves appear. When they're taken care of, go up the elevator. The security guard on the top tries to warn Gordon about the female assassins ahead, but then gets killed by them (who is the main character in Azure Sheep and doesn't die). Take the lovely ladies down with explosives and then check the area for batteries and charging stations (ammunition won't matter). Then go up the top platform and then use the switch to open the doors leading to the surface. As it turns out, the military has apprehended Gordon (alas the name of the chapter being "Apprehension",) and then the two marines talk about how they would torture Gordon. The choice was to put Gordon into a chamber with two walls closing in (a tribute to Star Wars apparently). Gordon MUST climb up the boxes to an area above. On the other side is another crowbar. Gordon lost all his previous weapons! When he obtains it, on the floor is a grate. Smash is and run through the tunnel to the next chapter.

This starts the other half of the game. Gordon must avoid obstacles in this chapter, as well as a few aliens. Ammo is scarce here.

First, Gordon should avoid the headcrabs that spawn from above and turn the wheel on the water silo. Then enter it quickly. Eventually, there's a vent to the interior of the waste factory. A security guard battles a pair of headcrabs. Collect the handgun round and then follow the guard, where he gets eaten by a barnacle. Get the handgun from whatever's left of his body and then return to where the dead headcrabs are. Jump across the nuclear pool. Simply jump across any pools of bad liquids and then swim across the water areas.

Gordon will come across more crushing machines and conveyor belts. Simply put, activate the switch and then kill the bullsquid in the office. Collect everything and then move.

I really don't like this chapter either. I'll make the story short. Gordon must dodge every obstacle he meets. He will then eventually come across a chamber full of barnacles. Avoid them and then proceed.

Here's where the action really recovers. This chapter has lots of stuff to try out and lots of lasers!

Go up, smash the grate and dispatch the houndeyes nearby. Shoot the generator to open the door. The next room contains a different type of vortiguant. Smash the glass blocking the button and kill the alien to open the door. The next place has some headcrabs in a box. Use the bunker's button to destroy the horde. A trooper comes in the room. Quickly lure him into the room and then kill him with the experimental weapon. Pick up his gun and then talk to the security guard ahead. He says that the area is locked down, and the only way to get out is to get a scientist to unlock the exit. He'll join Gordon as soon as he finishes his talk.

A lobby has a squad of men. Lob a grenade at the twosome walking away. Collect the shells on the table and then pick up the dead people's treasures. Then pick off the remains of the platoon. The next area is similar to the place with the weapon. The only difference is that the weapon SHOULDN'T be used and there's a button that unlocks two chambers containing headcrabs, a crossbow, and a bunch of snarks. Another couple of soldiers patrol the hallway. Take them down and go down the ramp, where the room has some terminals. Collect the tripmines nearby and plant them at the unopened chamber throw some satchels between the first tripmines and then shoot it. Once the vortiguant soldiers come up, shoot Gordon's tripmines. Then kill the other one. When the door beside the other alien opens up, detonate the satchel. After the brawl, get the guard to follow and then dispatch the trooper in the corner. The hallway leads to a door with a crazy-looking machine. Ignore it and go to a hallway with glass. Break one of the panes and run through. Have the guard to stay and run back. While the guard shoots the headcrabs that attempt to attack Gordon, he can break the boxes inside the room nearby. There's a tripmine at the end. When the headcrabs are all dead, go up the stairs.

Once up, shoot the bullsquids that attack and then go to the room on the right. Inside, turn on the button on the generator. This will emit a laser through the ceiling. Collect the batteries in the room. The path to the left leads to a conversation, where a security guard messes around with a secret weapon. The scientist demands him to put it down. Just after he tells the guard not to overcharge the weapon, the wall inside explodes. Collect the guass cannon the corpses leave behind and turn on the generator. Go back to the main hallway and go to the end, where a squad of hostile soldiers await. After dispatching them, collect the bounty in the boxes and in the room, as well as turning on that generator. The last generator is towards the left path, and inside the room, lots of houndeyes are here. When all four generators are turned on, go to a room to the left of the hallway (where Gordon is facing now) and then read the signs. Break the rules by grabbing a box and put it under the laser shield. This will make the shield go back up when Gordon activates the big laser and will destroy the wall. Jump down, using the pipes, boxes, and such.

Inside the room nearby, three scientists are here as well as a first-aid station. The first says that they should get out before more soldiers arrive. The second states that they have high access and can deactivate the lockdown. The third warns that Gordon needs to turn off the crazy machine before they can move (the fourth died because of that). At the end, there's a control panel that will turn off the machine. Get one of the scientists to follow and go through the "headcrab" hallway. Then turn right and open the door. There's a chance that a trooper will appear on the right of the lobby. When he's down, get the scientist to the scanner. Use the armor station. The scientist will warn Gordon that the area ahead is dangerous, full of military and alien fights. But if he makes it through, he'll come across the lambda team.

Outside, kill the marine and knock down the turrets on the roof. Then shoot the crates and move onto an area with crates. Break them open and open the door.

This is my favourite part of the game. It is also one of the longest. For the first part, use the MP5/M16 the most. I will explain later.

Here, some soldiers ambush Gordon. He should shoot the barrels they're beside to make things easier. After that, pick up all the stuff and then run to the end of the dam. Dodge the Apache’s and turrets attacks and launch a grenade at the turret. Then use the guass cannon at the Apache. The MP5/M16 also works, but not well. After the helicopter is down, go to the watery side of the dam and kill the ichthyosaur. Then go up the ladder on the tower and turn on the switch. Use the first-aid station if needed and go down to the bottom of the dam. Turn the wheel and go through the holes. Gordon will come through the dam and to the other side. Nab the battery beside the corpse and swim across the river. There should be some pipes that Gordon must enter.

After crawling through, another Apache appears in the skies! Break the boxes, climb up, and jump across. Collect the provisions and the jump across. Run across the ledge and try to take down the Apache. On the top, a houndeye takes the area. Kill it and go to the path opposite of where it came from. A platoon of soldiers are here. Take them all down and enter the building. Turn the wheel. Collect anything nearby and go to the direction that says "Minefield". Throw grenades on the area to detonate the mines. Then jump into the hole blocked off by the fence. Then climb through the tunnels.

The next place is a cliffside. Shoot the turret and the marine to the right with the crossbow. Then take down the trooper below. Climb down and dash across the cliffs, eliminating any soldiers. There's a large tunnel leading to a grunt, some supplies, and the Bazooka. Use the new weapon on the Apache that comes nearby. Climb up the cliffs and inside the pipe is a headcrab. Kill it and crawl in the pipe.

A note from Donald "Dch48 nick" Henderson:

"Right after you get the rocket launcher, you can run out and get the helicopter to start after you, then run back inside the cave. The 'copter will attempt to shoot rockets at you through the cliff and will actually blow itself up. You don't need to use any kind of ammo at all."

This area is filled with soldiers and a tank! Launch some grenades at the tank as well as rockets. Once the tank is down, dispatch the soldiers and collect the grenades and go behind the tank. There's a cache of explosives and a trooper. Collect, destroy, and return back. Go to the switch and press. Go through the newly opened door and take down the light tank with the bazooka. Break the crates for some hand grenades and jump through the hole on the right. Throw some hand grenades down and collect the stuff in the crates. Jump over the sandbags and into the door.

A vortiguant soldier lands on the left and a vortiguant slave appears on the right. Go to where the slave spawned and run through the hallway, jumping over the tripmines. At the other side of the building, a security guard struggles to get up. He's been hit by a sniper at a window. Shoot the sniper in the camouflaged window and pick up the guard's shotgun. Throw some grenades in the minefield to detonate the mines. When Gordon reaches the fence, he should shoot the sniper in the window. After that, shoot the barrels to destroy the generators, making it safe to climb the fence and the fallen tower. On the roof, there should be a hole. Fall in.

In the room, destroy the boxes. The scientist in the room warns Gordon about the next room. The building is full tripmines, and if one detonates, then it will cause a chain reaction! Jump over the first tripmine, and then climb on the stair banister to get past the second. Go to the door on the left, and climb the boxes and into the window. Shoot the two headcrabs and the box on the metal platform. There's a damaged box here. Destroy the damaged sides and go through the box. Crouch under the tripmine in the staircase and there will be a headcrab in the control room. Here, activate the switch. It will bring up the metal platform the box was on. Go onto the platform, and jump across and onto the elevator with the bronze platform. Then go down. Here, destroy the boxes and collect the ammo, and the hivehand if needed (which would hardly be). When Gordon proceeds through the hallway, a security guard runs away from his pursuers. Kill the soldiers on the chase and get the guard to follow.

Here, the truck contains a turret and a box with some energy cells for the Tau. In the large room with the large boxes, an explosion will occur. Don't let the guard get killed by it. Tell the guard to stay and go up the ramp and to the outdoors. Run up the other ramp to the boxes, fending off the vortiguant soldiers and break the boxes for first-aid kits and batteries. Then a plane will arrive, killing the Xen soldiers. Use explosives, the bazooka, or the Tau to take out the light tank. Then kill the soldiers beside. Get the guard to follow and then go up the far side of the building on the right. A sniper is in a window here. Lead the guard to the locked green doors and tell him to stay. Go to the main building and then kill the commando and the grunt. Destroy the tables and the radio, along with the boxes. Up the stairs is some beds and a guard, who will open a door for Gordon. This is why I wanted Gordon to spend his 9mm ammo. There's enough 9mm ammo here to fill Gordon up even if he exhausted his 9mm bullets. Also, there are lots of other types of ammo here. Break the boxes at the end of the room. There's a switch that will turn on the lights if necessary. Get the guard to follow Gordon and lead him to the other guard.

After that, go back into the building and jump through the window next to the shelf. Go across the ledges, jump across the generators, and climb up the broken ladders. On the top, throw all the grenades at the bottom. Once done, go down and unlock the door. Go back up the ramp and jump from ledge to ledge to the next area. The helipad is no place for the chilled. Go to the door across and ignore the vortiguant soldiers. Run down the ramp and jump the boxes. Use the turret to destroy the big door. When all the vortiguant soldiers are down, dewing the osprey flying across to prevent it from sending soldiers. After the osprey is destroyed, go to where the turret was and go down. Unlock the big green doors and get both guards to follow. One will unlock a door. Use the charging stations and break the boxes. Go to the new pathway, making sure the guards follow through.

Here, tell both guards to stay. Collect the 9mm ammo and use the turret to take down the vortiguant slaves. Lots of them spawn here. Get past them and use the jump pad to get to the upper floor. There's two vortiguants battling two soldiers. Take down the two and break the vent. A snark or two will come out. Use the crowbar on them and go up the vent. More snarks will come out of the infested area! Destroy them all with the MP5/M16 or the crowbar, and collect the snark packs. Destroy the grate and the soldiers will shoot the vents! Throw five snarks down and then run back collecting the rest of the snarks. By now, the squad should be finished. Wait for the snarks to explode, and then go into the room. Collect the bounty and the batteries. Open the door and run back, since a grenadier blows up the explosive box in front. When a hole appears in the wall, use the switch on the left to raise a platform. Before it does, however, jump on. Then jump through the hole, killing the grenadier and the commando. When they're done, use the turret to destroy the door and the vortiguant soldiers that come out. In the next area, kill the aliens and then throw all the snarks at the soldiers below. When they're done, go down and explore the "arena" for supplies. Climb back up and jump across the hole in the catwalks to the other side. Take advantage of the first-aid station nearby and proceed through the hallway. A vortiguant soldier throws a trooper through a wall. Kill the alien and watch some soldiers duke it out with some vortiguants.

When the aliens are down, snipe the soldiers with the crossbow. Don't forget to take out the trooper on the roof. Above Gordon's position is another alien soldier, so bring it down when he's off the building. Go to the gate and enter the shack. Grab the shotgun. Gordon needs a Black Mesa employee to open the door. Use the jump pad to get on top of the roof. Break the grate and then crawl through the pipe. Run back as soon as the trooper throws in a satchel charge. The watery area is the safest place to dodge the fire. Crouch through the pipe and kill the trooper. In the next room, lob a grenade at the fighting group. When they're dead, turn the wheel in the room to open up another pipe. Go inside and go through it. At the end, a trooper ambushes Gordon. Kill him and his partner at the bottom floor. At the top, a security guard waits. Use him to open the door at the bottom floor. Outside, a pair of vortiguant slaves spawn. Annihilate them and lead the guard to the post.

Get the guard to follow. In the garage, two marines get squashed by a Gargantua. Use the guard to distract it while Gordon runs for his life. The Gargantua will likely follow. Run through the garage without delay until he's outside, where he must use the jump pads to a water tower. The radio speaks. The man tells Cooper (the dead guy on the tower) that the military is pulling out and using air strikes. The map in front is for designating targets for the missile barrages. Use the map to take down the Gargantua. After the mighty alien, use it on the bunker door, the walls, and the radio tower. Climb across the tower towards the door. Run through the road toward the next chapter.

This is the last chapter featuring the soldiers. Also, it is very short compared to the last chapter.

The chapter starts with some fragile ceiling rocks. Wait for three to fall and then jump on the third one and across to the door. A radio announces that the soldiers are on the retreat. If needed, use the switch to turn on a turret. Unfortunately, it also turns on Black Mesa Personnel as well as aliens. The security guard will die if the turret is activated. But infinite aliens spawn here. Anyways, go down the roads, searching for ammo in the infested walls. There's some cocoons that hold some nasty snarks. They block the way from rooms that have ammo and supplies. Go left after going down the ramp and kill all the vortiguant slaves. Go up and turn the wheel. Note that this will destroy the cocoon and will unleash some snarks. Once in the sewers, Gordon must deal with some headcrabs and turrets. Once they all die, use a crate to get to the left side. The right is the wrong way. Take down the barnacles in the sewers. Kill the headcrab nearby. Once back in the water, avoid the Ichthyosaur and go to the machinery. Crouch under the gear and under the water. Eventually, Gordon will come across a turret. Knock it down, and take out the trooper next to the bazooka and rockets. Climb up the ladder after grabbing the rockets and use the bazooka on the tank. Also, there's a trooper and a commando here. When the tank's done, fill up on the rockets and crouch through the door, knocking down the turret. Go to the elevator after using the first-aid station.

Here, jump over the anthrax. There's a battery or two inside this place. At one point, there's a commando and a trooper here. Kill them and go through the hallway and collect the medkit. In the arena, use the tank's turret to destroy the door. There's some supplies in the boxes. Slip past the soldiers and the aliens and go through the door on the left. Note on the way, there's a Xen turret. Destroy it with the bazooka. The left hallway leads to the door leading to the Lambda core.

From here on, there's no more soldiers. But as long as it's on earth, it's still fun!

Gordon must use the control panel ahead and then go down the elevator. Clear the area of aliens and collect any goodies here. In the next room, deal with the female assassins. Go up the stairs to the upper tier and go down the elevator.

Destroy any vortiguant soldiers on sight in this hangar. When they are all slain, a scientist opens a door for Gordon to get through. He explains that he waited for Gordon to clear the area and that all other entrances are locked down to fend off the alien invasion. Most of the other team has retreated to the core and to other safe areas. The Lambda team is waiting for him. Gordon should go to the locked door to have the scientist open it for him. Collect the crossbow bolts and go up the elevator, using the charging stations nearby. Go right and collect the gluon gun. The scientist nearby is the one who invented it, but gives it to Gordon because he is a pacifist. If necessary, Gordon can open the target areas to test out his new toy. Grab the energy cells and go to the elevator.

Down, some aliens have already invaded the Lambda reactor! Kill any of them and go to where two vortiguant slaves are observing a corpse. Kill the pair and go right. A guard is waiting. It is not necessary to use him, but if it makes Gordon comfortable to have company, then be my guest. Down the stairs is a scientist, who says that the only way up towards the central Lambda Core is to flood the reactor by turning on the pumps. There, use the charging stations and collect the supplies. Go back up and follow the blue trail on the walls. This leads to the first pump. There, a vortiguant slave ambushes behind Gordon somewhere along the run. In the room, destroy any vortiguant soldiers and collect any supplies. Go up the ladder and through the door. There, avoid the headcrabs and turn the wheel on the generator. Go back to the central area. The second pump is leaded by the orange trail. Treat this like the first pump, except that there's more enemies there and some barnacles. Also, a part of the catwalk will collapse. When both pumps are activated, go back to the supply room. The scientist tells that both pumps are on and that Gordon must hurry to the reactor. Take any leftover supplies. Go to the other passage and fight any aliens that get in the way. In the room, an infinite number of vortiguant grunts spawn here, so fend off enough to jump into the pool and swim through the hole.

Flood one pump at a time. Only do the next one when the first is finished, or else the pumps won't work and it's game over for Gordon! With the water level high, Gordon can climb the ladder. Note that the reactor explodes and emits a crazy electrical beam. Avoid it and get through the vortiguant slaves to the top. Go into the supply room and then go up the elevator shaft climbing the ladder to the upper level. There, go into the security booth and tell the guard to follow. In a dead-end, Gordon can see how the G-man can get along with dead- ends. There's a wheel that will turn on the steam where Gordon can lure Aliens and kill them with the steam, saving ammo if needed, but don't kill the guard with that! Kill any aliens that spawn and go to the next area. This place has teleports everywhere! The more coloured teleport spheres are the entrances, while the more pale ones are the exits. Go into the entrance (when a rotating platform is under the exit) and be prepared for a little mini-game! The entrances that are required for Gordon to go through is 2,4, and 7. Avoid going through 1,6, and 9, 1 teleports Gordon in a headcrab field. 6 transferes Gordon to a fall, taking some of his health away. 9 kills him completely. The others load Gordon to rooms with ammo, so go to those ones if needed.

When Gordon goes through the final teleport, he spawns in a chamber where he needs to activate two switches to get to the centre and teleport out. Go for switch one first, because when turns on the two, that's the angle where he needs to teleport. If he does it the other way around, he'll need to start all over again. To get from switch to switch, jump across the rotating platforms and back. Don't fall into the anthrax. When Gordon teleports, he appears above the teleporting machine. Go to the door. Climb the ladders and such, collecting supplies along the way. When up the final ladder, Gordon will come across the entrance to the central Lambda core! On the other side of the door, Dr. Kleiner and a guard are surprised by Gordon's arrival. Kleiner opens the door for him to get through.

Kleiner explains that single creature is responsible for teleporting aliens to Earth. To stop the invasion, Gordon must travel to the alien's dimension, Xen, and bring the creature to justice. He also says that his colleague is working on the teleport in the next room and will transport Gordon to the borderworld. He then gives Gordon a long-jump module, where he can jump at great distances. Collect the supplies and the long-jump pack, and get the guard to follow. Kleiner can also follow. Use the charging stations and go to the next room. Kleiner's buddy is using the controls and needs to be covered to open the Portal. Don't let him perish, or else it's the end of the game! Go up the ladder at the other side. There, when the scientist begins activating the Portal, kill any vortiguant controllers that spawn in the dome. The best weapons to take care of these are:

-MP5/M16.
-Egon cannon.
-Tau.
-Revolver.

When the scientist announces that the teleport is ready and demands Gordon to jump through. When he does, a lone soldier busts in...

Nothing I hate more than traveling in Xen. This area has lower gravity than Earth's and has LOTS of platforms.

Gordon starts on one of the many platforms surrounding a huge platform. From here, try to jump from platform to platform, until Gordon lands on the main one. Among the cracks on the platform's walls is the entrance to the interior. Jump in and Gordon will find himself among shallow water and three small towers. First, there is a bit of netting surrounding some flying objects. Smash it and open the towers. The three pieces will get attracted to the towers, and will create a Portal in the middle. Jump in!

It keeps getting worse and worse. Now we have awful music on our hands as well as the borderworld!

Once Gonarch (the spider with a huge sack underneath) is in sight, use the MP5 Grenades, Rocket Launcher, and any other explosive or other powerful weaponry against Gonarch. Gonarch will eventually fall back. Do the same here, and don't fall into that hole. Pursue Gonarch once more to its lair.

Fall inside the pit and get all the supplies down there. When Gonarch comes down, use everything against him! When Gonarch is killed, fall down, heal in the pool, and get down to the teleport.

Thank heavens the music has stopped! Unfortunately, this chapter is less annoying but more difficult. Survive this!

Gordon must fight his way to the opposite end of the island. From there, get into the cave and kill the Vortigaunt. Heal in the pool, and then fall in the hole and hack through the web-things. Crawl through the tunnels and into a cave -like area.

Don't land on the rock in this "room". Jump to the other end of the cave and kill any aliens there. Nab the supplies and head up, then through the little hole in the wall.

Destroy the webbing to make the pillar fall. Then get on. Once Gordon steps on the pillar, he will be sent flying sky-high. Once the "elevator" is at its maximum height, jump from platform to platform until Gordon reaches the stationary platform with the supplies and blood on it. When a manta-like aircraft appears, jump on it and then jump to the teleporter.


Walk out of the cave and use the Crossbow to kill the two Vortigaunt Soldiers on the hills. Get into the other cave to find some angry Vortigaunts and Supplies. Get out to find some Vortigaunt Controllers.

Get into the huge hole in the wall and plant some Tripmines on the narrow path. This will get the attention of a Gargantua, so run away and plant some Satchel Charges. These and the Tripmines will be able to destroy the Garg. To the right is a cave with a Battery and some Snarks. To the left is an outdoor area with Tentacles (from the Blast Pit level) that make the narrow path dangerous to cross. Use Grenades to distract it and keep long jumping to the other end of the pathway. Kill the two Alien Grunts and move into the teleporter.

Gordon will find himself in a factory. move up the elevators, killing any aliens in the way. there will be healing rooms on some of the floors. notice the conveyor belts carrying the huge barrels. get onto the one that sends the barrels down.

Get out of the pool ASAP. The aliens will notice Gordon's Presence. Don't destroy any of the barrels (they contain Vortigaunt Soldiers). Near the pool, climb up the tiny platform to get to the next floor. Run towards the conveyor belts and get through the narrow passage.

Move on towards the next elevator. Destroy the barrel and kill the Soldier inside. Avoid destroying the rest of the barrels in this area. However, the barrels in the next narrow corridor will need to be destroyed, so plant the Tripmines near the barrels and then throw a grenade. Collect the supplies near the dead body after killing the aliens in the next area. Replenish some lost health and then crawl through the small holes.

Keep crawling through and be ready to slaughter the aliens in the next huge room. Go up the ramps and get onto the nearest elevator. On this floor, Gordon can go through the holes in the walls to find some supplies. Keep moving up the platforms in the previous room until Gordon can jump into that floating Portal.

Here's the final boss! The most annoying part in this chapter is that the alien can teleport Gordon to rooms. These rooms are very tall and Gordon must climb up the platforms on the walls to get back.

Jump across the platforms and jump into the Portal on the throne. Here, try to destroy the nearest Orange Crystal in sight (these three need to be destroyed). Also, make sure Gordon gets attacked by Nihilanth 2 times with the Portal so that he won't have to do that again.

One of the teleportation’s requires Gordon to jump across the platforms until he reaches the Portal. Another requires Gordon to kill all the enemies and climb aboard a ball that floats to the return Portal. However, this can be avoided by taking cover behind a pillar (or the portals can be shot). This is also how Gordon can avoid taking too much damage from this alien's electric attacks.

Once all of the crystals are destroyed, try to get to the top balcony. To get there, Gordon must find the jump pad nearest to the tallest balcony. Jump in order to actually make it there. Unfortunately, Nihilanth will teleport Gordon once again. In this room, be sure to kill the Ichthyosaur, then get back up and kill the Vortigaunts. Search the place for any necessary supplies, then use the centre jump pad to get back to business! Repeat this process and kill the Garg in the next teleportation.

Once Gordon's up at the top for the THIRD TIME, fire at Nihilanth. His head will open, so fire anything in there! He'll explode, and Gordon will be teleported somewhere else.

Congrats! The game is now complete! This is the ending! Save before the fork in the road to be able to get BOTH endings!

The G-man has stripped Gordon of his weapons, but has allowed him to keep his H.E.V suit. He says that Xen is now free of Nihilanth's influence because of Gordon and praises him. He explains why he is with him; the G-man told his employers everything and are interested in hiring him and his potential. Here's where it gets more detailed. The G-man offers Gordon a choice: Either step into the Portal and get the job, or wait and die on Xen without defences. Save at this point to get both endings!

It's the end!