Entry Hall

Follow the corridor into the main entry hall of the alien research labs. Kill a pair of Grunts standing in the foyer, and then kill a third Grunt that runs into the area. Get their weapons; one has a Shotgun. Charge up at an HEV Station, and then proceed across the entry hall. Take a corridor up a short flight of stairs to a balcony overlooking the entry hall. Upstairs, walk into a room, but make sure you leave the Security Guard behind. Press a wall button to release a bunch of Headcrabs, and then enter a booth in the corner and press a button to fry most of them with an energy pulse. Kill any remaining Headcrabs with your Pistol, and then enter the two chambers they originally occupied. You'll find a Crossbow in one, and some Snarks in the other. Take both. Follow a new corridor (take along the Security Guard if you left him behind earlier) and descend some steps to a T-junction. Take a right, and kill a pair of Grunts. Proceed to a large room with computer banks, Laser Mines guarding a corner and some interesting alcoves. Take a pair of Batteries from one wall, and then follow a small corridor to a balcony overlooking the room. Don't disturb the Laser Mines set up in the corner of the room.

When you're up on the balcony, take out your Pistol and shoot one of the Laser Mines on the other side of the room. Slide back from the balcony as they explode. Two Alien Grunts and several human Grunts now enter the room separately, and they'll slug it out. Try to go unnoticed while this is happening. Kill any survivors that try to climb the ramp to your balcony; then descend back into the large room. Walk through the doorway the Laser Mines guarded. Proceed down the corridor, wary of the Grunt that will try to ambush you. Eventually you'll come to a junction with a room full of crates ahead and another hallway to the right.

If you enter the crate room, save first and then break the crates slowly and carefully; a Laser Mine back here will detonate if you destroy the crate it's aimed at. Now take the hallway to the right. Beware the four glass-walled alcoves flanking this hallway. Headcrabs burst from behind glass to attack as you cross. Kill them all. When the Headcrabs are gone, take the hallway that intersects with this one between the two sets of Headcrab-filled alcoves. As you climb the stairs, you can hear breaking glass and the sounds of fighting. Peek into the long hallway at the top of the stairs and then duck back into the stairwell. Grunts and Bullsquids are fighting in the long hallway. Stay back until the fighting dies down.

Powering up the Laser

Enter the long hallway and take the first right. You'll enter a small lab room. Kill any enemies you find there, take two Batteries from a ledge and press a red button to send a white energy beam into the ceiling. Return to the long hallway and take the next left. Explosive crates lie ahead. You'll hear a conversation between a Scientist and a Grunt. Stand well back from the explosive crates. After a moment, the crates explode, and a moment later a second explosion takes place ahead. Walk forward toward the source of the explosions into another lab. Collect a Tau Cannon from the floor, and press a console button to activate the second white energy beam.

Re-enter the long hallway. Ignore the next right and take the next left into another lab, this one infested with Houndeyes. Kill them all and activate a third white energy beam. Return to the long hallway and enter the final lab. Collect some Tau Cannon ammunition from a wall, use a First Aid Station and turn on the fourth and final white energy beam. Investigate the crates stacked at the end of the long hallway. There are probably a few Grunts holding out back there, but you'll find valuable Combat Rifle grenades in the crates. Return to the lab you skipped earlier and enter. Slide the metal crate flush with the wall, under a sign that says "Do Not Obstruct Laser Shield." Press a red button on a console at one side of the room. A laser shield tries to descend from the ceiling, but if you positioned the metal crate correctly, the shield is blocked and forced to go back up. The red laser beam shoots the wall instead of the shield, blasting a hole. Jump down through the hole the laser made. It's a long drop, so save the game first. Then leap onto a pipe located about a third of the way down. From there, drop onto the lower section of the same pipe, and from there to the floor.

Escape

Walk into a small room with three Scientists. Listen to them, but don't have any of them follow you. Approach an adjoining room with spinning metal blades mounted on swing-arms. Cross through the blades to the other side of the room. Activate a console on the other side of the room to stop the blades. Stop them so the walkway across the room is clear. If the blades block the path, start them again with the console and then stop them again at the right moment. Retrieve a Scientist and have him follow you across the room, through the motionless blades.

Open the door on the other side of the room by pressing a nearby control panel. Go through. In the corridor beyond, take a left and then a right. You'll run through the corridor where Headcrabs attacked you earlier. Go all the way to the end of this corridor, round a bend and pass through a door. You're back in the entry hall to the alien research labs. Run to the Retinal Scanner and let the Scientist open it for you. Listen to him, and then exit. Pass through a revolving door to an outside area. Kill a nearby Grunt and two Tripod-Mounted Chainguns on a rooftop. Shoot a pile of explosive crates from a safe distance. Go through the tunnel they blocked. Break crates in the tunnel for gear. Approach a large door to end the level.

Surface Tension

Trouble at the Dam

Press the button and walk just through the sliding doors, but no farther. You're looking at a canyon where fuel barrels lie scattered in clusters. Grunts wait in ambush to the left and right and several more hide farther down the canyon. Kill the Grunts to your right and left. Then turn your attention down the canyon. Instead of shooting Grunts, you can shoot the fuel barrels they're standing next to and clean them out quickly. Pick up the ammunition and First Aid Kits the Grunts left behind and advance down the canyon. Walk beneath a rock arch to where you can see a dam ahead and hear an Apache Helicopter flying above. Stop. Remain in this semiprotected rock alcove while the Apache flies back and forth overhead.

After hiding in the alcove for a couple of minutes, equip the Crossbow, save the game and dash toward the dam when the Apache isn't pointing at you. Run straight for the reservoir and jump into the water. The Helicopter and Artillery Gun will fire at you, but you'll be more or less unscathed if you get into the water quickly. Underwater, swim down several feet, out of sight of the Apache. Immediately look for the Ichthyosaur and shoot it with multiple Crossbow bolts to kill it. If you allowed the Apache to soften it up earlier, it shouldn't take much. Look for an underwater ladder. It's attached to a tower. Climb the ladder when the Helicopter isn't too close. Hurry! At the top of the ladder, run into a small room that has a First Aid Kit and a wall button labeled "Turbine Control." Press the button. Then, when the Apache isn't too close, leap from this room back into the reservoir. Underwater, locate a valve wheel. Turn it to open a pair of underwater grates. You must turn the wheel for several seconds to open the grates wide enough to swim through.

Swim through either grate and duck past the stalled turbine rotor. You'll be swept into a small river. Collect a Battery from a nearby rock, and then proceed downstream, ducking underwater when the Apache gets close. The river terminates at a ledge. Climb a ladder to the ledge, and enter either of two pipes there.

Fortification in the Sand

Follow the pipe until it terminates in a steep, artificial canyon. You can either take a left or go straight ahead; an Apache still buzzes overhead. Take a left, kill three Headcrabs and collect a First Aid Kit near a dead Grunt in a dark cave. Then backtrack to the pipe and go in the other direction. You'll find a ladder and several crates. Break the crates for ammo, and then climb the ladder to a ledge. Leap across the ledge to a broader, sand-covered ledge that holds a dead Grunt, a cactus and a lot of supplies. This is where you'll make your stand. Get out the Tau Cannon and charge up its secondary fire mode when you hear the Apache coming. Give the Apache a highly charged Tau Cannon blast. If this doesn't bring it down, give it another and another. After downing the Apache, jump back to the narrow ledge and follow it around a corner. You'll come to a ladder near the end. Climb it and walk forward.

Two paths lead through the rocks. Both lie on your left. Approach the rocks and take the closest path to find yourself in a sandy gulch with a Tentacle." Draw your Pistol and fire several rounds into the Tentacle. It will rise straight up, thump the sand once, and then hide for a few seconds. Run close to it as it hides, and you can collect valuable gear strewn on the sand. Quickly get away before it reemerges. Shoot it again, and make another mad dash if you missed anything good. Backtrack and take the other path through the rocks. This path leads to another sandy gulch. Instead of another Tentacle, this gulch contains three Grunts. Kill them all.

After killing the Grunts, enter a small structure with a valve wheel labeled "Storm Drain Hatch." Turn the wheel. Investigate the gulch. The rocks have several crevices you can crawl through to get supplies. Beware the Grunts' hideout, however; there's a Laser Mine set up inside. Proceed with caution and you'll do fine. One of the crevices leads to a new area filled with mines. Your goal is to reach a storm drain surrounded by barbed wire. To get past the barbed wire, climb up on a sandy hillock right beside it and jump over. Climb a ladder down the drain, smash a grate at the bottom, and crawl through a tunnel.

Vertigo

As you approach the end of the tunnel, a jet flies past in front of you. Halt and watch it go by. Don't drop out the end of the tunnel. Instead, peek out and to the right. Shoot a Tripod-Mounted Chaingun on a distant ledge by popping in and out of the tunnel, firing periodically. Also, kill a Grunt to the right. Now drop out of the tunnel to a small ledge. You're standing on a sheer cliff wall. Look over the left side of the ledge. Below you lies a narrow ledge and below that a broader ledge with a Grunt on it. The Grunt is barely visible; shoot him. Then drop down to the narrow ledge, and from there drop to the big ledge with the dead Grunt on it. Look down from this ledge. Below, you'll see two more ledges: a long, narrow ledge, and a wider ledge farther down. Drop to the narrow ledge.

A crevice in the cliff wall near the narrow ledge contains a dead Grunt and some First Aid Kits. Jump over some rocky debris to claim the First Aid Kits. Get back out onto the ledge. Look down from the extreme left-hand side of this ledge where it gets very narrow, and you'll see a series of narrow ledges leading down. Leap down two of these steps, and then jump to the broad ledge below them. Make that last jump a long one. Approach a rickety bridge. Save the game, and then run across. The wooden planks tend to fall apart as you cross the bridge, so it's easiest if you line yourself up on one of the metal cables supporting the planks on either side, and cross on that. Round a bend to see a big metal platform. Ignore it. Keep following the ledge, killing a Grunt as you go.

You'll round another bend and find a cave with a Grunt guarding it. Kill the Grunt and enter the cave quickly. Smash crates and collect gear, including a Rocket Propelled Grenade Launcher and several rockets. You'll hear an Apache hovering outside. Wait in the cave entrance for the Apache, and then shoot it with the RPG. If this doesn't destroy it, hide in the cave until the Apache makes another pass, and then shoot it again. When the Apache's gone, make sure you have everything from the cave, and then continue along the ledge. You'll find a ladder. Climb to a higher ledge. Follow the higher ledge to a ramp. This in turn leads to a short series of ledges, like stairs. Jump up these steps to another ladder. Climb this ladder to another ledge, and on to a pipe sticking out of the cliff wall. Approach the pipe, kill the Headcrab inside, and follow the pipe into the cliff.

Combat

The tunnel eventually reaches a T-junction. From there, the tunnel branches into a complex network of foxholes that riddles a fortified area filled with Grunts and a single Tank. From that first T-junction, take a right. Follow the tunnel as it curves left and drops you into a trench with shallow water. Wade forward, ignoring a path that leads to the right. Jump into another tunnel at the end of the trench. When this tunnel reaches a T-junction, take a right. Follow the tunnel to the end, and climb a ladder. Now you're in the fortified Grunt compound behind the Tank. Don't worry about it as long as you're behind it. Just concentrate on killing Grunts. When all the Grunts are dead, break all the crates behind the Tank and heal yourself at a First Aid Station in a garage. You'll collect a lot of great stuff from the crates, including more RPG rockets and some Satchel Charges. Destroy the Tank with a Satchel Charge, and scour the fortified compound for ammo. Locate a small shed with a wall button in it. Press the button to open a big door leading out of the compound.

Exit through the door, into a long street with crates on both sides, and a Tank that shoots rockets at the far end. Destroy the Tank and then break all the nonexplosive crates along the street for Batteries and grenades. Leap through a hole in the wall beside the dead Tank. On the other side, kill a pair of Grunts standing at the bottom of a sandy ravine. When both are dead, go break boxes at the bottom of the ravine. Return to the street with the burning Tank. Walk to the end of the street and go through a big garage-type doorway into an alcove, and then through a second garage-type doorway.

Ordinance Storage Facility, Exterior

Pass through the second big door to find yourself in an enclosure around an Ordnance Storage Facility. An alien craft flies overhead and drops an Alien Grunt and a Vortigaunt. Kill both aliens and take a right. Round a corner and destroy a Laser Mine stuck to the wall. Then advance to a small stairway. Stand back as some rubble falls from above, and then go down the stairs. There's a Laser Mine at the foot of the stairs, and on another small staircase leading up. You can jump over both, but save the game first. Past the Laser Mines, you'll come across a dying Security Guard lying out in the open. He cries for help, but don't approach him. Instead, turn around. Look up to see a partially camouflaged hole in the wall, and if you look very closely you'll see a gun sticking out. Throw a Grenade up there and kill the sniper before proceeding. Approach another sign that warns of a minefield. Throw a Grenade into the minefield to detonate mines, and then advance to a corner.  

Throw another Grenade around the corner to detonate more mines. Save the game and move forward. There's another sniper in a hole in the wall up ahead; you must take him out with a Fragmentation Grenade or Combat Rifle grenade. Throw one more Grenade to ensure there are no mines ahead. Then walk up to a section of barbed wire so low you must crawl under it. Two metal towers stand on the other side of the wire; one leans against the Ordnance Storage Facility. Some explosive barrels lie beside a pair of power converters. Shoot the explosive barrels from a distance, destroying the converters and "de-electrifying" the towers. Jump up on the leaning tower and walk to the roof. Locate a gaping hole in the roof there. You must jump over a rooftop fan to reach it.

Storage Facility

You fall into a room with a Scientist. Listen to him, and then break all the crates in the room and walk out the door. Outside, you'll see a hallway filled with Laser Mines. Jump over the first Laser Mine. Push a wooden crate to the foot of a short staircase. Jump onto the crate, and then jump from there to the top of the staircase, thus avoiding a second Laser Mine. Jump across a third Laser Mine and proceed, ignoring a metal door to the left. You'll approach a big, open area. Crawl under a Laser Mine into the open area. Look for a pair of Headcrabs in the middle of this area and shoot both with your Pistol before they trigger any Laser Mines. Take a left. Approach the boxes. Destroy the leftmost box, but stay well away from the box with the laser shooting at it. Walk around the laser, through the area you just opened by destroying the box. Approach another box, destroy it and jump over a Laser Mine behind it.

Proceed to the concrete wall, take a left, and climb a short, red-tinged staircase. Upstairs is a small control room. Kill a lone Headcrab with your Pistol, and then jump over a Laser Mine to reach a wall button. Don't press it yet. Turn left from the button to see the top of a crate. Shoot the crate and it will crumble. Now turn back to the button and press it, summoning a lift to your left. Board the lift. Then jump down onto another lift surrounded by metal bars and Laser Mines. It's a tough jump, but you can make it. Press a button to descend.

Downstairs

You descend into a room filled with crates. Collect a Hivehand on the floor and goodies from the crates; then get moving down a tunnel. As you walk through the tunnel, a Security Guard runs past pursued by two Grunts. Kill the Grunts, preferably by shooting explosive barrels near them. Proceed along the tunnel, leaving the Security Guard behind. You'll encounter a truck. Destroy a Tripod-Mounted Machine Gun in the back of the truck. Then jump inside, collect some ammo from a crate and get moving again. You'll enter a basement area. An explosion rocks the place. Save the game and run up a ramp, out of the basement and into an open, outdoor street area. Immediately run either back into the basement area or up the ramp to the right. An alien ship soon drops Alien Grunts onto the street. Shortly thereafter, a jet drops bombs that kill them all. Needless to say, you should be hiding as all this happens, or you'll get fried. After the bombs drop, peek around the corner to see a pair of Grunts and an artillery-firing Tank at the end of the street. Hide and let the Grunts come to you; then destroy the Tank with your Tau Cannon's secondary fire mode.

After destroying the Tank, walk up to it. Then follow the street to the right. You'll enter an alley. As you do, turn around and throw a Grenade up into a hole in the wall behind you to kill a sniper. Walk down the alley and enter a door to the right. You'll enter a small room with two Grunts. Kill the Grunts and climb a short flight of stairs. Upstairs, walk up to a Security Guard and have him follow you to a locked door labeled "Storage." He'll open the door. Beyond lies a veritable candy store of ammunition. Collect ammo from racks and break boxes. By the time you're through, you'll be at or near maximum ammo capacity for almost every weapon. Exit the storage room and walk back to the stairs. Don't go down. Instead, approach a window and walk out on the window ledge. Take a right on the window ledge and follow it back into the alley. Drop onto a pair of electrical converter boxes just below the ledge. Jump from the converter boxes onto a second pair of converter boxes across the alley. Jump from them onto the piece of red ladder nearby and climb the ladder. Climb a second ladder to the top of the wall.

Bigger Guns

You stand on a platform above a maze of twisted and broken walls. Go to the right side of the platform, near a beam that descends diagonally to ground level. Equip your Crossbow and look over the edge. Kill a Grunt down there. Slide down the beam to ground level. Kill two more Grunts on the lower level, collect some First Aid Kits from a dark alcove, and then walk back up the beam. Cross the maze to a doorway out of the area. First walk out to the lone piece of ceiling, then leap from there onto some broken walls, and from there to the doorway. The doorway leads to an open courtyard. Two Alien Grunts materialize as you start to cross; kill both. After killing the Grunts, cross the courtyard. Go through a tunnel and take a right to confront another Alien Grunt. Kill it and then leap up a series of nearby crates. Upstairs is an Artillery Gun. Use it to blast a hole in the compound's front gate. Send a couple more shots in the same direction to kill two Alien Grunts behind the door.

Run through the door you just blasted open and down a corridor beyond. You'll come to a hallway with several Vortigaunts and a Heavy Machine Gun. Shoot the nearest Vortigaunts with your Combat Rifle, then slide up to the Machine Gun and Use it. A series of Vortigaunts will now teleport into existence down the hallway. Use the Machine Gun to mow them all down. Be patient, as there's a slight delay between Vortigaunt appearances. When all the Vortigaunts are gone, and no more seem to be forthcoming, proceed to the end of the hallway. There you'll find what looks like a giant, spongy growth on the floor. Step onto it: it's sort of an alien trampoline. Use it to jump up to a crumbling ceiling level.  

Approach the edge of the ceiling; several Grunts will shoot at you. Back off and take shelter. The Grunts will battle an Alien Grunt and a Vortigaunt. Approach the edge again and kill the stragglers. Drop to where the Grunts and aliens were and collect First Aid Kits from a stack of crates. Shoot out a small grate near the floor and crawl through. As you follow this tunnel, a pack of Snarks springs toward you. Retreat when they appear, and deal with them using either a rapid-fire weapon or explosives. Go to the end of the ventilation tunnel and smash a grate.

On the Run

After smashing the grate, back up immediately. A pair of Grunts below shoots out a section of ventilation duct, which falls to the floor; you won't fall if you backed up far enough. Shoot the Grunts from up here, and then drop to the floor. You're in a small garage. There's a metal door on one wall. Open it, and then back up quickly. An explosion blocks the doorway and rips a hole in the wall. There are two lifts in this garage, but only one has a vehicle on it. Press a button hanging from the ceiling near the lift without a vehicle. That lift descends. Press the button a second time and hurry onto the lift, which rises. Now you can see through a big hole near the top of the garage wall. Shoot two Grunts through this hole, and then jump through it. Outside, there's an artillery cannon. Use the cannon and blast a hole in a big door ahead. Keep shooting through the ruined doorway; several Alien Grunts behind the door will try to emerge.

When all the Alien Grunts are dead, go through the doorway you just blasted open. The hallway beyond leads to a balcony above a huge warehouse. A big fight is going on down on the main floor. Stay back as the fight rages, allowing both sides to weaken. Kill any survivors, and then descend a ladder to the warehouse floor. Collect gear from a small room off to one side, plus any ammo from the dead Grunts. Climb back up the ladder. Leap across a gap in the balcony and proceed through a door on the other side. Take the hallway beyond, past an Alien Grunt that knocks a hole in the wall to get at you. Kill it, and then look out over an open outdoor area. Kill any enemies you can see from up here, and then drop onto a pile of crates. Downstairs, scour the outdoor area for more enemies; then jump onto a rooftop with a giant alien "trampoline." On the roof you'll find a grate. Smash it and drop through the floor.

Inside

Drop through the grate into a shallow pool. Follow a tunnel away from the pool. When a Grunt at the far end of the tunnel opens a hatch and drops in some explosives, back up all the way to the pool and submerge during the explosion. Again, enter the tunnel. This time, go to the end and kill the Grunt. Proceed to a balcony overlooking a room where Grunts battle Headcrabs. Let both sides slug it out, and then advance along the balcony. Jump onto a pipe with a valve wheel on it. Turn the valve wheel and then back up as a hatch opens. Go through the newly opened hatch. Follow the pipe beyond the hatch until it ends in the middle of a staircase. Kill a Grunt, and then go upstairs. You'll find a Security Guard up here. Have him follow you. Go downstairs. Kill another Grunt, and have the Security Guard open a door. Pass through the doorway and walk down a hall. You'll find yourself back in the open outdoor area. Approach the checkpoint and run inside the small guardhouse, keeping the Security Guard with you. Have him press a console button in there to open a metal door. Go through the metal door and into a parking garage.

Incoming

As you enter the parking garage, a Gargantua appears to your left and smashes a pair of Grunts. Flee to the right. Don't wait for the Gargantua to start coming toward you: just go! Eventually the parking garage gives way to an enclosed outdoor area. There's a big wall here and an alien trampoline. Use the trampoline to jump across the wall and steer yourself into a convenient water storage area on the other side. Climb onto the rim of the water storage area and walk along a narrow pipe to the top of a high tower. Atop the tower is a radio and a map of this outdoor area. The radio informs you that you can call in air strikes with the map. Play with the map's controls to see how they move the targeting crosshair. If the Gargantua followed you out here, it will approach the wall and stand there for a while before trying to smash through. Using the controls to either side of the map, move the crosshair into position more or less where the Gargantua is standing.

Press the central button several times to unleash air strikes on the targeted position. Watch where they fall. If they don't hit Gargantua, move the crosshair and try again. Now move the crosshair over to the wall. Launch an air strike. It should break a wall protecting a corner of this area. If it misses, tweak the crosshair and try again. When the wall's demolished, place the crosshair over the door. Launch an air strike. It should break open a large door beyond the broken wall. As always, adjust the crosshairs and try again if the first strike misses. Save the game and then drop to a ledge near your tower. Leap from there through the wall you just took out with an air strike; go through the door you just destroyed. Follow the corridor beyond to a short stairway. Go up the stairs to another corridor, and the next level will load.

Forget Freeman!

Turret Troubles

Immediately after this level loads, you'll walk forward into a garage area. A door closes behind you automatically, and chunks of the ceiling start to fall. Slide back and press against the door that just closed behind you, making sure to stand near dead center of the door. Jump over the debris and go out the room's only exit. You arrive in a guardroom elevated slightly above a large open area. A radio spouts messages, and you'll find a wall-mounted lever and a computer. Jump down to the main floor. Note that you can get back into the guardroom by leaping on a broken piece of concrete near the wall. Locate a Security Guard and have him follow you farther out onto the main floor. You'll encounter some Alien Grunts. As soon as they engage you, run back to the guardroom. Throw the wall lever to activate a Turret on the ceiling of the main floor. Then remain near the wall by the lever, crouching to avoid enemy fire. The Turret will destroy some of the Vortigaunts and Alien Grunts entering the area.

When no more enemies are visible, turn off the Turret and return to the main floor. Kill any aliens down here. Down on the main floor, you can jump on a pile of crates to get over a railing to a First Aid Station. Jump back down when you're finished and walk into new territory. Follow the main floor to a T-junction with a stop sign. Take a right instead. After taking a right, you'll pop up in a hall with some Vortigaunts. Kill the Vortigaunts with the help of an explosive crate, and then walk out onto a small bridge over water. Flee from the Snarks that pop out of a sphere on the bridge and return in a minute. Walk across the bridge and turn a valve wheel. A hatch opens. Descend the ladder beneath the hatch.

Underwater

Downstairs is a small room with a Headcrab. Shoot it before it triggers a laser beam that activates a Tripod-Mounted Machine Gun, and then destroy the Machine Gun. Go through a short tunnel. You'll emerge in a room with two shallow canals. Break a crate in the middle of the room for a First Aid Kit and then jump over a low grate guarding one of the canals. You'll land in the water on the other side. Swim down the canal and take a left onto a small walkway. Follow the short walkway to another watery area. Now you can jump into the water again and go either left or right. To the right is deep water with an Ichthyosaur; avoid it. Go left instead, into a shallow section. The shallow section leads to a massive gear. Swim under and through the gear, and then through several underwater pipes.

You'll come to another gear. Swim under it to approach a small area with a Tripod-Mounted Machine Gun and a Grunt behind. Destroy both and get back on land. In a small alcove you'll find several RPG rockets and a ladder leading up. Climb the ladder to an outdoor area with two Grunts and a Tank. You'll have a tough fight; kill the Grunts first while hiding from the Tank and dodging Grenades. Then take out the Tank with several RPG shots. Walk past the ruined Tank into an alcove with an elevator and a Tripod-Mounted Machine Gun. Destroy the Machine Gun and descend in the elevator.

Tank Commander

The elevator takes you down to a corridor covered with radioactive waste. It ends in a T-junction. Take a left there, hopping over waste, to collect a Battery. Then return and take the other path. You'll approach a platform with two Grunts on it. Kill both and collect a First Aid Kit from a nearby alcove. Get on the platform the Grunts were on and go down a short hallway to a warehouse. There an immobile Tank and several Grunts are fighting Alien Grunts. Hide as the two forces slug it out; then kill the survivors and jump down to the main floor. Collect ammo from crates. Climb a short ladder up onto the Tank. Use the main Tank Gun once to fire it and blast away a door. Then Use the Tank's Machine Gun to gun down a host of Vortigaunts and Alien Grunts that appear near the ruined door.

Cautiously walk through the door you destroyed with the Tank Gun, and then run backward when several Alien Grunts from the hallway beyond start shooting at you. Dispatch the Alien Grunts with conventional weapons or Tank weapons. There are still Alien Grunts both to the right and left of the hallway beyond the door. Return to the hallway and kill a lone Grunt to the right; then focus on both an Alien Grunt and Energy Cannon to the left. Walk past the destroyed Cannon and operate a wall panel to open a massive sliding door. Walk through the door and press a button on the other side to open a second door. Walk through it.

Lambda Core

You appear in a room with a truck on a lift and a control booth to the right. Enter the booth, press the button and ride down on the lift with the truck. Downstairs, kill several Headcrabs and a Bullsquid. Break crates for ammo and climb a ladder to a raised platform. Go through small a metal door labeled "Hazardous Material Handling Bays." The corridor beyond the door leads to a massive room filled with explosive barrels and crates. A big catwalk looms overhead. Four Assassins inhabit this room, so you should spend awhile cautiously exploring and killing anybody you find. Try not to expose yourself to fire from above, because two of the Assassins tend to stay up on the catwalk. On the right side of the room, several breakable crates block a corridor. Break the crates, go upstairs to the catwalk and dispatch any Assassins you find up there. From the catwalk you can locate a stairway leading down. Take it to gain access to First Aid and HEV stations. Go back upstairs when you're through.

Follow the catwalk into a dark area with an elevator. Take the elevator down. Downstairs is a massive, semicircular tunnel. Open the big doors at one end. An Alien Grunt appears behind you as you open these doors; another appears in front of you. Kill the Alien Grunt behind you by shooting explosive barrels near it, and then take on the one in front. Two more Alien Grunts appear in the same general area after you kill this one. When the Grunts are all dead, climb a ladder on the other side of the room. This leads to a small room with a Scientist. Listen to him and watch as he uses a Retinal Scanner to open a door. Go through the door. Use the First Aid and HEV stations beyond, and then go up a short lift. Upstairs, take a right at a T-junction. Enter a lab with a Gluon Gun and a Scientist. You can press buttons to release monsters and test the Gluon Gun on them, or simply take the Gluon Gun and ammo and leave. The second choice is wisest if you want to conserve ammo. Return to the T-junction, and this time take the other path to an elevator. Take the elevator upstairs.

The Core

The elevator takes you to the core of the Lambda reactor. You appear on a balcony overlooking pools of coolant. The hallways here are conveniently labeled; follow the corridor with a blue sign that says "Coolant System 01." Follow the corridor down a ramp and around a bend. Take a right and cross a bridge over a pool of coolant; another blue sign that reads "Coolant System 01" tells you you're headed in the right direction. The corridor leads to a big coolant chamber with three Alien Grunts in it. Kill all three, and then climb a ladder to a catwalk. Follow the catwalk to a room labeled "Pump Station 01." In the Pump Station, kill Headcrabs and Vortigaunts, and then activate a lever labeled "Pump 01". A large reservoir below fills with water. Return to the main balcony. Follow the yellow signs leading to "Coolant System 02." Follow the rubble-filled hallway to "Coolant Station 02," a large room that looks much like "Coolant Station 01," except for the Barnacles on the ceiling and a crane hoisting a heavy pipe. Kill the Alien Grunts and Barnacles, and then climb a ladder to the catwalk.

Follow the catwalk to a hallway to "Pump Station 02." There's a dangerous steam leak in this hallway; turn a nearby valve wheel to stop the steam so you can cross freely. Kill the Barnacles and assorted aliens in "Pump Station 02," and press a lever to fill a reservoir below you with water. Again, return to the main balcony. A sign on the wall should now indicate with lights that pump stations 1 and 2 are operational.

Flooding the Reactor

Locate a hallway leading to a T-junction where signs read "Maintenance Area" and "Aux. Tank Reactor Access." Take a right into the Maintenance Area. Descend a flight of stairs to a small room with lots of ammunition and a Scientist who urges you to hurry. Collect ammo, return to the T-junction, and this time take the hall labeled "Aux. Tank Reactor Access." This hall leads to a room with several Alien Grunts and a deep pool partially filled with coolant. Kill the Alien Grunts, and then descend a ladder into the water. Swim through a tunnel labeled "Maintenance Access to Main Reactor." Halfway through the tunnel you come to a small chamber where you can stop for air. Surface, and then proceed through this chamber to the main reactor core. There are two valve wheels underwater near the main reactor core. Turn one, and the water level rises. Swim to the surface and shoot a Vortigaunt prowling the upper levels of the reactor.  

Save the game and then turn the second valve wheel. This sends the water level high enough that you can swim to a ladder. It leads to a series of platforms connected by ladders. Your goal is to ascend to the door at the top of the reactor. Traveling bolts of electricity shooting from the reactor make it difficult to reach the top. Instead of rushing up ladders in a mad dash for the top, halt halfway up each ladder and watch the bolts of electricity as they move around. You'll avoid most bolts easily if you watch them pass, and then climb the rest of the way up the ladder when the coast is clear. After ascending a ladder, always take a right. This leads you around the platform to the next ladder. There's a particularly nasty bolt of electricity near the door at the top. Wait for it to subside before running through. Finally, if you're have too much trouble, save the game every time you make it up a new ladder.Follow the corridor to a door labeled "Supply D-301." Get supplies from this room, and then climb a ladder in a nearby elevator shaft.

Teleportation

Upstairs, take a right at the sign that says "Lambda Reactor Core Level B." Get supplies from another supply room, and then return and take a left. Walk past a room with a Security Guard in it. Take a left at a T-junction to catch another brief glimpse of the dark-suited man. Return to the T-junction and take a right. Alien Grunts teleport in ahead and a Vortigaunt appears behind you. Retreat to familiar territory and kill them all as they give chase. A valve wheel in this hallway controls a steam leak farther down the hall. Turn it to turn on the steam. It will damage any Alien Grunts that try to get through it. Before you reach the steam leak, there's a room on the left with two teleporters in it. Walk into the yellow teleporter sphere and you'll reappear in the green one. When you're done experimenting, go past the steam leak almost to the end of the corridor. If you see Alien Grunts, backtrack and turn the steam back on to kill them. Proceed when the coast is clear again.

Down the corridor and to the right you'll find a door. Enter it. Behind the fence is a column with nine little doorways called "Ports" cut into it. Each Port teleports you to a different location, and each is numbered. Ports 1 through 3 are on the lowest level of the column, 4 through 6 are in the middle, and ports 7 through 9 are at the top of the column. Floating platforms circle the column. You must stand on them to jump into the Ports. How to start: Walk onto the yellow teleporter sphere in this room, and you'll reappear near the green sphere next to the column. Time it so that one of the floating platforms will be below your feet when you arrive at the green sphere, or you'll fall and have to start over. Watch those moving columns before walking into the teleporter! You've teleported onto the moving platform, ride it around and enter the column through ports 1, 2, or 3. Each leads to a different location.Rreach the next level of moving platforms and gain access to ports 4, 5, and 6, enter Port 2, which teleports you up to the next level of moving platforms.

Port 1 leads to a small area with Headcrabs and radioactive waste. You can collect Grenades here, but unless you're especially keen on Grenades, avoid it. Port 2 teleports you up the next set of moving platforms, so you can enter ports 4 through 6. Three leads to a small room stocked with Batteries, Satchel Charges, and other great stuff. Highly recommended! Four teleports you to the top set of moving platforms, so you can access ports 7 through 9. Five sends you to a room with three Scientists. You can collect lots of gear if you do a little exploration; this, too, is recommended. Six leads to a damaging fall. Avoid it. Port 7 sends you to the next phase of this level, so take this Port only when you're ready to move along. Port 8 takes you to a small room overlooking the reactor you recently flooded. A couple of Vortigaunts will harass you, but an HEV Station and some ammo for your Tau Cannon might make this worth the trip. Port 9 kills you.

Visit any of the nine Ports. Bear in mind that whenever you use ports 2 or 4, you should leap in from near the front of your moving platform. If you enter the Port from near the back of the platform, you'll miss the higher platform when you teleport and take a nasty fall. When you're finished experimenting and collecting gear, go through Port 7. (Do this by teleporting onto the lowest row of moving platforms, taking Port 2 to the middle level, taking Port 4 to the highest level, and then entering Port 7.) You see a bizarre teleportation core.

Beyond!

Save the game. The teleportation core in front of you consists of a central core, two sets of small, fast-moving platforms and a ring-shaped platform that constantly moves up and down. Make your way onto the ring-shaped platform, using the outer set of small platforms to get there. Walk along the ring until you see an alcove with a button labeled "1." When the platform is high enough that you can easily jump there, do so, again using the small outer platforms to assist you. Return to the ring-shaped platform and walk around it until you see another alcove, with a button labeled "2." Cross into the alcove and press the button. Return again to the ring-shaped platform. The blast shields guarding the central teleportation core now have slid back far enough that you can jump inside. Jump over to the central core and hop inside to teleport. You materialize in a small room. Go out through a doorway.

Enter a corridor blocked on both sides by rubble. Climb the ladder in an alcove. Upstairs you'll find a set of glass doors. A Scientist admits you. Listen to the Scientist and Security Guard on the other side of the doors. Collect lots of gear from the rooms on the other side of this door. Be sure to collect the Long Jump Module, which allows you to take those long jumps you practiced in the Hazard Course. When you've got all the gear you can carry, go through the door into the amphitheater-like main teleportation chamber. Inside, locate the ledge you must run onto to teleport. It's distinguished by its guardrail, and by the fact that it extends almost into the middle of the teleportation device.

The Scientist in charge explains that he mustn't be distracted, or the teleportation procedure will fail. As he speaks, look for a ladder to a tall ledge overlooking the area. Climb it and get out your Gluon Gun. As the Scientist starts the procedure, several flying Xen Masters teleport in. Methodically kill them with the Gluon Gun, staying up on the platform and dodging slightly to avoid Xen Master shots. If you aren't fast enough, the Xen Masters will kill either you or the Scientist; if the Scientist dies, the whole room explodes. If you're fast, eventually the Scientist will tell you it's time for you to go. When he does, quickly descend the ladder. Leap into the yellow sphere in the center of the room and teleport to Xen.

Xen

Culture Shock

You appear on a small chunk of rock floating in the sky. Far below is a huge floating rock you'll want to visit eventually. There are two other chunks of stationary rock floating in the sky nearby. Use your Long Jump to leap to the first rock; then shoot a Vortigaunt on the second rock and jump there. Another Vortigaunt and a Houndeye materialize on the second rock after you jump there. Kill both, and then study the numerous moving platforms floating above the massive central rock. From the third rock, you must leap to the closest moving platform, and then from platform to platform until you can safely land on the giant rock below. Remember, you can jump extraordinary distances now that you have your Long Jump Module.

When you've reached the top of the giant floating rock, you'll notice there isn't much to do there. That's because all the action is inside the rock! Look for a moving platform hovering slightly below the top of the giant rock, and jump down onto it. From the platform you just jumped to, you can see the interior of the rock. Jump to it and start exploring. Eventually you come to a healing pool. Nearby is a hole in the wall. Crawl in, stand up and break a wall of moss over a larger hole. Jump into an inner chamber. Inside, three small columns or pedestals stick out of the ground. Approach each and Use it. A diamond-shaped object atop each pedestal will open. Look for something resembling a cage of moss, with three flickering specks of light flying around in it. Smash the moss cage with a crowbar to release the specks. The three specks settle eventually on the three pillars you just Used. A pillar in the center of the room energizes, in essence becoming a teleporter. Walk into the newly created teleporter.

Gonarch's Lair

You appear in a large, open area. Nearby is a dead man in an HEV Suit. Batteries and a case of assorted ammunition lie beside him. Take the Batteries, but not the ammunition; immediately look for a place where a tall rock rises, near the "edge of the world." When you find this rock, you'll see a narrow space between it and the edge of the world. Walk behind the rock, so that you're protected from the Gonarch. You should be able to see a healing pool; long-jump to it whenever you're injured. Start shooting the Gonarch from behind the rock. If you're lucky and the Gonarch stands in the right spot, you can shoot it through a crack in the rock where you're extremely hard to hit. Eventually you'll deal enough damage to the Gonarch that it flees, breaking through a wall and running down a tunnel. Collect the ammo from dead man in the HEV Suit, heal yourself in the healing pool and follow the Gonarch down the tunnel. Collect a Battery and some ammo along the way. Eventually the tunnel ends in another open area. Stay back in the tunnel, avoiding the small, whipping tentacles, and shoot a few RPG rockets into the Gonarch. It will charge down the tunnel toward you. Do your best to leap aside and run out into the open area.

Circle-strafe around the open area, firing Combat Rifle grenades and other high-powered ordnance at the Gonarch. Note that there's a hole in the middle of the combat area, partially obscured by vines. Take care or you'll fall through! Eventually you'll deal enough damage to the Gonarch that it breaks down another wall and flees. Don't follow it yet. Instead, look for a small hole in the ground, not the larger, vine-covered hole in the center of the area. Drop down the small hole and walk into a central area with a hole in the middle and two other ledges. Jump to the left ledge and heal yourself in a healing pool in a chamber beyond it. Return to the central area and jump to the other ledge, where you'll collect some ammo and find a trampoline that takes you back to the main level. Approach the hole the Gonarch ran through. Jump down into it, but take care to leap to a ledge on the other side of the hole, instead of dropping all the way down in a single fall and injuring yourself.

Drop down into the pit. The Gonarch sits above, like a spider on a web. Circle-strafe around the pit, firing RPG rockets and Combat Rifle grenades at the Gonarch, and avoiding miniature Headcrabs. When you've shot the Gonarch enough, it drops from its web. Let 'er have it with more heavy-duty weapons; if you have any ammo for the Gluon Gun, that's ideal. A few seconds of Gluon Gun fire should do the trick. As the dead Gonarch crumples to the ground, a hole opens in the floor. You can leap right down into it and teleport to the next level, or look into it first and locate a ledge above the teleporter. If you leap to the ledge instead of all the way to the bottom, you can use a healing pool. Jump into the teleporter when you're done.

Interloper

Early Troubles

The ledge you appear on starts to crumble. Before it does, quickly look around. Note the floating platform with the teleporter on it. That's your eventual destination, but you can't get there yet. Now turn in the other direction. Note that, although this world is mostly flat, there's a big ridge in the distance. Run toward the ridge, ducking in and out of the cover of the giant columns. Vortigaunts pose your greatest threat, not your enemies in the sky. Kill any Vortigaunts that get too close, but don't try to kill them all; just use the columns for protection, and run as fast as you can when you aren't behind cover. A cave entrance lies on one side of the ridge. Run into the cave and kill a Vortigaunt. There's a healing pool just inside the cave. Use it, and then drop into a tunnel. Break some vines covering a nearby hole, and then fall down the hole into a horizontal tunnel. Take this tunnel to a room where massive spikes slowly rise and fall from the ceiling and floor. Kill a pair of Headcrabs and cross this room quickly, or the spikes will trap you momentarily, and damaging green gas clouds will discharge from the ceiling.

Proceed through a tunnel to a large cavern with Barnacles overhead and a Bullsquid in a corner. Kill the Barnacles and the Bullsquid, and then examine the room. You'll encounter First Aid Kits, a dead man in an HEV Suit with some ammo nearby, and a walkway into another chamber. The new chamber contains a curious-looking column partially obscured by vines. Shoot away the vines and the column starts to descend. Save the game. When the column reaches the bottom, get onto it and ride it back up. You'll be carried up into the sky. Shoot any nearby Xen Masters on your way up. At the top, immediately look for the nearest moving platform and drop down onto it. Be sure it's the highest platform available, or you'll take falling damage. Continue dropping from moving platform to moving platform. After dropping to the fifth moving platform, pay close attention to the kite-shaped alien creatures that glide across the sky.

As you draw close to one, jump onto its back. Position yourself squarely in the middle and crouch, making it difficult for the Vortigaunts on the ground to hit you. The alien glides slowly toward the teleporter. Shoot any Xen Masters that appear overhead, and any Vortigaunts that have a clear line of sight at you. Eventually you'll be close enough to the floating rock with the teleporter that you can hop on. Do so and enter the teleporter.

Caverns

You appear in a cave. Walk to its exit. To the left is a wide-open area where two Alien Grunt overseers stand on a pair of hills and a few working Vortigaunts mill around beneath them. To the right is a Tentacle in a pit, and beyond that, a cliff wall with a hole in it. Take a right and approach the pit with the Tentacle, but don't go so close that the Tentacle can slap you. Shoot the Tentacle once with the Crossbow to make it sink from view momentarily. While it's down, long-jump across the pit it's rooted in. You'll land on a small ledge beneath a cliff wall. There's a hole in the cliff above you. Turn around and shoot the Tentacle a second time with your Crossbow to keep it down. Then jump up into the hole in the cliff wall. Crouch at the top of the jump to get a little extra height. The tunnel beyond the hole leads to a small cavern with a waterfall, a healing pool and two Barnacles overhead. Heal yourself in the pool. Then jump up onto a ledge on the side opposite where you entered. Follow a short tunnel.

The tunnel leads to a new cavern we'll call the middle cavern. Look carefully at the screenshot of this new area. On the extreme left is a narrow ledge you can jump to and climb up. Do so, and you'll collect some ammunition. Go back down the ledge. Approach the exit on the right-hand side of that figure, but don't go through it. It leads back outside. From this exit you should be able to see a Vortigaunt or two on the ground and two Alien Grunts standing on low hills, like overseers. Use the Crossbow's zoom feature to snipe the Alien Grunts. An alien craft is likely to drop two more Alien Grunts outside at this point. Kill both and proceed outside. There, you'll notice the mouth of a cave in one of the hills the Alien Grunts were standing on. Equip your Shotgun and go inside. You must kill several Vortigaunts in there, but you'll also collect lots of valuable ammo.

After collecting all the ammo, go back outside and return to the middle cavern shown. From there, either return to the healing waters of the waterfall room, or proceed through the cracked, narrow entrance. This entrance leads to a tunnel blocked with boulders. Jump up on the boulders; a Gargantua charges toward you. Instead of retreating, run past its legs and take a right. Dart into a hole in the wall where you'll be safe. There's a Battery and some First Aid Kits in here, as well. Look out from your hiding place. You'll see the pacing Gargantua and a hole to the outside. Wait for the Gargantua to run to the left, away from the hole; then dash out and approach the hole. Jump up on the low rocks in front of the hole. Then long-jump from here across a chasm. This is a tricky jump if you rush, because you fear the Gargantua, so try to keep your movements calm and smooth. You have more than enough time to make the leap. Across the chasm is a semicircular ledge. A pair of Tentacles emerge from the ground nearby. Shoot a Barnacle overhead.

Drop a Satchel Charge into the Tentacles' hole and detonate it so that they both retract. Then follow the ledge, using a long-jump to cross a broken part. Continue past a third Tentacle. The ledge leads to a small cavern with a teleporter and two Alien Grunts. One of them is hidden behind a rock at first. Kill the first Alien Grunt with a surprise attack; then locate and kill the second. Collect Satchel Charges and Laser Mines from the floor of this cavern, and then enter the teleporter.

The Mines

You appear in a small room with broken machinery. Take the only tunnel out. The tunnel leads to a massive mine chamber where Vortigaunts labor to move huge barrels around. Explore the lower level of the mine, collecting a stray Pistol clip and First Aid Kit. Then board a massive lift that continually travels up and down near the center of this room. Ride up to its first stop and get off. On this level you'll find an alcove with a blue, phone-booth like structure in it. Get inside to heal yourself. When you're at full health, return to the giant lift. You want to ascend farther, but don't get on the actual lift part. Instead, jump onto the top of the ring that supports the lift. Ride this ring all the way to the top, where you'll see a pair of conveyor belts with barrels on them. Jump to the nearest conveyor belt. It carries you toward a central span that connects the two belts. Cross the span to the other conveyor belt and let it carry you into a hole in the wall. Stand close to the nearest barrel in front of you. You'll fall off into a shallow pool of water. Immediately scramble out of the pool and drop to the floor, or the barrel behind you will fall and crush you.

Multiple Targets

Kill a Vortigaunt and a Xen Master hovering nearby, and then investigate the floor. You'll find an alcove that leads to a ledge overlooking a big chasm with a blue healing cubicle you can restore your health with. Near the spot where you fell into the water, you'll find a small lift that takes you up a floor. Ride it up. Walk along the conveyor belt here into a new area. Several Xen Masters and Vortigaunts attack from the new area; stay back and fight conservatively, proceeding only when the coast is clear. Follow a balcony to a spot where a huge, piston-like column rises and falls repeatedly from a hole in the floor. Ride up on this column. Upstairs is a roughly circular balcony. Both ends terminate in a long hallway filled with barrels, but one end is blocked. Take the unblocked path into the hallway and kill several Vortigaunts and a Xen Master in there.

Walk down the hallway. Several Vortigaunts hide in nooks and crannies and Xen Masters fly overhead. Proceed methodically. After turning a corner, you'll reach a spot where you must break a barrel to proceed. Do so, quickly kill the Alien Grunt inside and enter a new room. It contains several Xen Masters and Vortigaunts. Kill them, and heal yourself at the blue healing station. Locate three reddish ducts near floor level. Enter one and follow the tunnel beyond. The tunnel ends in a vertical shaft with horizontal bars shot through it. Drop down this shaft from bar to bar. Follow the tunnel at the bottom.

Ascent

Eventually you confront two holes in the floor. Save the game, load a potent weapon, and drop through either hole. You'll drop to a ledge overlooking a huge abyss. Xen Masters float overhead and Vortigaunts walk on ledges above. Do your best to avoid shots and return fire. You can move off to the right and hide in a corner, if you'd like; this cuts down on the number of enemies that can see you. When all visible enemies are dead, follow the ledge to a short ramp up. Take the ramp and kill more Vortigaunts. You'll find a blue healing chamber on this level and a disc-shaped lift mounted on a pole. Get on the disc and ascend. Upstairs, get off the lift and kill more Vortigaunts and Xen Masters. Then look for a spot where two sections of balcony enter the wall with a slight space above them.

Take another pole-mounted lift up to another set of ledges. Kill more Xen Masters and Vortigaunts. From here you can follow the ledge to a side room and enter a blue healing chamber. When you're fully healed, take a final pole-mounted lift to the top of this massive cavern. Jump off into the glowing green teleporter. The teleporter deposits you in a bizarre landscape of floating rocks, with a gnarled, evil-looking structure in the distance. Jump from floating rock to floating rock to the evil-looking red structure. Jump to the rock supporting it. Jump into the glowing red teleporter at the center of the structure. You'll whisk away for a final showdown with the Nihilanth.

Nihilanth

You appear in the arena. Drop to floor level and hide behind a giant floor spike: one close to the wall, not the center of the arena. Behind the spike you can avoid Nihilanth projectiles. Occasional Vortigaunts or Xen Masters might show up to attack, but you can kill these easily from back here. Shoot the three glowing yellow spikes sticking out from the walls above. If you can't get a good shot at all three from your current position, quickly run from one position of cover to the next, always just after the Nihilanth attacks. Eventually you'll reach a spot where you can see the third yellow spike, and destroy it. Hammer the Nihilanth with concentrated weapons fire, ducking in and out of the cover of a big spike as you do. Conserve your Gluon Gun ammo, but feel free to fire other weapons. The RPG and the Crossbow, both of which deal great damage, are recommended. After you've damaged the Nihilanth a lot, no more glowing spheres will revolve around its head. Continue picking away at the Nihilanth with the Crossbow or other, lesser weapons. Eventually the flesh of its skull will peel back like the skin of a banana, revealing a glowing sphere that is its brain.

Run to the trampoline beneath the higher of the two ledges on the wall. This trampoline will get you the lift. Use it to jump high in the air. The Nihilanth instinctively will try to rise and match your height, but for a few moments you should be higher, with a direct view down into its brain. Hose down the brain with continuous Gluon Gun fire. If this doesn't kill the Nihilanth, use the trampoline again and shoot the brain some more. Eventually, you'll deal lethal damage.

You might expect that you've won when you kill the Nihilanth. Most of the endgame sequence is non-interactive; that is, you can't affect it one way or the other. At the very end you have a choice: either jump out into the darkness, or stay in the vehicle you're standing in. Just for fun, you'll probably want to see what happens as a result of both choices. The choice which gives you the closest thing to a happy ending is to jump.

 Espero que t'hagi agradat aquesta guia i que t'hagi estat util per poder acabar aquest joc.

Half Life