Half Life Walkthrough

Half Life is one of the first First person shooter games. Its release in 1998 was record breaking at the time, and with the release on both PC and PlayStation 2 the game sold over eight million copies.http://planethalflife.gamespy.com/hl/ The game contains puzzles as well as basic first person shooting and combat. There have been further expansions released, but the Half Life fan base has stayed strong. This game has won over 50 awards since it's release. The graphics of the time were improved with the release of Half life

The story line follows the movements of a physicist that has been performing experiments and has accidentally caused what is being called the "resonance cascade". This accident has unleashed aliens and caused death and destruction at the lab where he performs these experiments. This means that this scientist is forced to combat the aliens that are from another planet as well as dealing with the hazardous waste clean up. The clean up crew is there to clean up the mess and they have no limits on what they will do to reach that goal. The tests that the player will face as Dr. Gordon Freeman will test the gamers puzzle and combat skills.

Dr. Gordon Freeman

Once the disaster has occurred the physicist, Dr. Gordon Freeman, needs to try to make things right. The retinal scanner is malfunctioning so he is able to get into all the otherwise off limit areas. This will aid the gamer in the task of dealing with the aftermath.

As the player works through the maze of laser lights and security devices they will want to keep their eyes open for weapons that can be used now and later. Crowbars are a good first tool as it is located in one of the first rooms that the player will access.

Watch for health dispensers so that Dr. Gordon Freeman can be kept alive as he moves all around the complex searching out aliens and beasts. Search the lockers and the rooms for any tools that can be used to keep the Doctor alive.

Cheats

To use cheats, run the game through the command line using the following command: hl.exe -console -dev

In the game, use the ~ key to open up the console in the game. You may need to type sv_cheats 1 prior to being able to use any cheats.

God mode - /god

All weapons with full ammo - /impulse 101

No clipping mode - /noclip

Obtain item - /give [item name]

Map select - /map [map name]

Item Names

item_antidote

item_healthkit

item_security

item_suit

ammo_9mmAR

ammo_9mmclip

ammo_buckshot

ammo_egonclip

ammo_glockclip

ammo_mp5grenades

weapon_357

weapon_9mmhandgun

weapon_crowbar

weapon_gauss

weapon_handgrenade

weapon_mp5

weapon_quantumdestabilizer

weapon_satchel

weapon_snark

Map Names

Single player

c0a0a

c0a0c

c0a0e

c1a0a

c1a0c

c1a0e

c1a1a

c1a1c

c1a1f

c1a2a

c1a2c

c1a3

c1a3b

c1a3d

c1a4b

c1a4e

c1a4g

c1a4j

c2a1

c2a1b

c2a2a

c2a2b2

c2a2d

c2a2f

c2a2h

c2a3a

c2a3c

c2a3e

c2a4a

c2a4c

c2a4e

c2a4g

c2a5a

c2a5c

c2a5e

c2a5g

c2a5x

c3a1a

c3a2

c3a2b

c3a2d

c3a2f

c4a1a

c4a1c

c4a1e

c4a2

c4a2b

c5a1

Multiplayer/Deathmatch

bounce

lambda_bunker

stalkyard

undertow

Hazard course

t0a0a

t0a0b1

t0a0c

Half Life Run Through Video

Save Cancel

URL | Web Search

Select a video

Half-Life in Half an Hour

source: www.youtube.com

This video shows a player that is able to clear the game in less than thirty minutes. This will assist the players as they maneuver thorough the game in the quest to rid the complex of the aliens that have been released.

This run through will give you some tips and provide some help when you run into more complex areas of the game. There will be some of the best hints available to the player by watching this video. It will explain some of the moves and steps to be taken in order to clear the puzzles in this game.

Training Room

This level isn't required but it does teach you the basics.

Use the W (or whatever you set your forward key to be) to move towards the hologram.
Use the A or D key to sidestep the hologram, or use the mouse to turn the camera and continue moving forward.
As a concluding not, S will make you move backwards.
Walk to the door and when a light shines on it go through it.
Walk up to the orange suit to equip it and continue out the opposite side.
Follow the path along some catwalks and what not until you reach the next hologram.
Move forward and use SPACEBAR to jump over the pipes.
Exit out the door and around the corner.
Hold CTRL to crouch and move forward under the pipes.
Move to the next area where you jump one pipe, crouch under the next, and jump the last one.
The next area, follow the catwalks and stand in front of the tube.
Jump and while in the air crouch and move forward to get inside.
Crawl out the other side and drop down.
Repeat the strategy for the last 2 pipes.
After leaving the room, use the same method to get into the pipe in the wall.
Walk past the hologram and up the ladder.
In the next area you learn to time jumps for max distance.
The jumps get further as you go, so be patient and jump to the far side.
Head to the next hologram and grab the object next to it on a table.
Climb up the ladder.
This takes a bit of practice, but run to the ledge.
Before you reach the end hit crouch and then jump.
Continue along the path until you reach another ladder.
Climb down this one then into the elevator at the bottom.
Press the button using the E key.
Jump down onto the target to notice that the game has falling damage.
Continue to the next hologram and use the health kit on the wall next to it by holding down E.
When you reach 100HP, continue through the door.
Follow the path to the next hologram and use the wheel on the right.
The bridge will slowly rotate back so jump onto it and off the other side in one move.
Continue to the next hologram and push the box (by moving forward into it) until it falls into the hole.
Run across the box you pushed in and continue to the next hologram.
Hold the E key and pull the box backwards.
Continue down the newly opened path.
Push the little box into the middle box and then to the large one so they are all aligned.
Jump up the boxes to the next door.
Grab the crowbar and use LEFT MOUSE BUTTON to attack the boxes in your way.
Crouch and attack the grate on the floor.
Drop into the vent and climb the ladder on the other side.
Grab the 2 packs on the table.
Press F to turn on the flashlight.
Follow the path and grab the power cells.
If you fall, there is a ladder near where you start.
You can try for the room with the guard but you don't need to go in there.
Continue along the path until you see a door.
Go into the room on your right.
Grab the gun on the table an all the ammo you want.
Enter the next room and listen to the hologram's instructions.
Shoot the target by the tube on the right back corner.
Shoot the target coming from under the platform towards the green boxes.
Shoot the target moving between the stacks of green boxes.
Shoot the target through the breakable glass on the right wall.
Turn around and shoot the target bobbing up and down.
Shoot the target moving behind the pipe behind the last one.
Use RIGHT MOUSE BUTTON to shoot a grenade over the unbreakable glass and hit the last target.
Exit up the stairs.
Walk off the platform and into the water.
Swim along until you see a hologram.
Follow it up and out. (If you need health)
Continue along the waterway until you hit a loading screen.
Jump out of the water and follow the path.
use the H.E.V. kit to replenish your shields.
Follow the path and learn the dangers of heat.
Exit through the door and up the ladder in the room with hazardous waste.
Follow the path, push the button left of the doors, and then the buttons inside the elevator.
Walk to the guard and press E to get him to follow you.
Get the guard to use the panel by the door.
Follow the path and jump on the tram.
Press the use key (E) to activate it.
Use forward (W) to shift to the higher gears and backward (S) to shift to lower and reverse.
Notice if you move sideways you no longer control the speed until you hit the use key again.

Black Mesa Inbound

Long tram ride to start us off.
If you didn't play the Training Room, get a feel for the controls.
If you are familiar with the controls, enjoy the sights and see if you can find the G-man.
After the lovely tour of Black Mesa, you get to wait for the guard to take his sweet time opening the door for you.
Walk down the catwalk and again, wait for the guard to open the gate.
After the door is opened, go inside, wait for a loading screen, and exit out the other door.

Anamalous Materials

Take the hallway until your reach a 4 way intersection.
If you follow the hallway straight, you will see the G-man in a window on the left.
You are free to explore, but the way to go is right.
Take the right path all the way down to a door.
Go through the door into a locker room.
Use the panel near your suit in the back left area.
Check the locker nearest the bathroom to notice your name on it.
Open it up using E and grab the energy pack inside.
Exit the locker room and follow the hallway past where you came in to have a guard open a door for you.
Go through the doors and down either path.
When you get to the opposite side, check the inner wall to find a door.
Press the button on the left of the door.
Walk into the lift and turn right until you see a button on the corner.
Press the button and descend.
Go through the door and follow the hallways until you reach a room with a bunch of scientists.
One will eventually open the other door and let you go on.
Use the button next to the door on the right.
Use the button on the wall near the lift and exit out the bottom.
Follow the path through a door to a room with 2 scientists.
After they open the door for you, go inside and climb up the ladder on the right wall.
When the red cover moves up, press the button and climb back down.
Head over to the opposite wall where you find a crate.
When the red lights on the cage flash get ready to grab the sample.
Walk behind the cart and push it into the beam.
Watch the experiment and a few things afterward.

Unforseen Consequences

Jump through the blasted door you came in and use the panel on your right.
Wait for the door to open and then go back into the hallway.
Follow the path back to the elevator and go up.
Go through the door and get the scientist to follow you to the retinal scanner.
Go into the next room and watch some lightning blow open the next door.
Time your run and head into the next hallway.
Rundown the hallway, past the headcrab that falls from the ceiling, and through a door on the right.
Crouch and follow the left wall to avoid the laser.
Move slowly until there is another explosion creating a second laser.
Run under it when it is moving along the ceiling and grab the crowbar next to the door.
Break the glass and crouch through the door.
Move through the next area and go through the door the same way.
Head up the ladder on the left wall.
Once at the top, turn around and press jump to land on the ledge.
Kill the zombie scientist and walk over the guard's body to pick up a pistol.
Kill the other zombie scientist and continue down the hallway.
Follow the hallways until you see two enemies at the far end.
Use your pistol to take them out, then kill the one sitting along the right wall.
Follow the path back to the locker room and grab the energy pack in your locker, ammo in a locker near your suit, and use the health box on the wall next to the sink.
Go back to the lobby area where you first started and a path will present itself.
Crouch and go through the hole.
There is a health box on the right as you enter if you need it and there are a few headcrabs.
Go through the vents in the back left of the room.
Drop into the next hallway and check out the rooms on both sides (nothing there but exploring is fun).
Continue along the hallway and grab the pistol from the guard on your left.
Use the health box if you need it then crouch through the door.
Listen for the new enemies (Houndeyes) as you press the button and go through the next door.
Use your crowbar (since they run away when attacked they won't attack you) and feel free to stop and watch the vent high on the wall on the right.
Follow the path and if you are looking up you'll see the G-man on a balcony after going down some steps.
Kill 2 more houndeyes and use the health box in the room on the left if you need to.
You can go through the door in the back right corner (Kill the headcrab that jumps you) and go up a ladder (use your pistol on the canisters that say "Danger" to kill the enemies) and guide the scientist on the right to a panel down the left path and grab amm0, health, and grenades.
Take the left path and watch out for the Vortigaunt that blasts out of the door in front of you.
After you kill it there is some ammo in the room it came out of.
Drop down through the hole near the gate and kill the crab.
Follow the path right and use the wheel.
While the water rises, find the vent on the ceiling and use your crowbar to break it so you can get out.
Kill the zombie and enter a large room.
Grab the ammo by the guard and use the lever next to him.
Quickly get on the lift and either kill the crabs or watch them fly off.
If you are like me and watched them fly off, run to the left when you reach the bottom and next to the catwalk.
Jump on the pipes on the right wall and follow them to the other side.
When you reach the other side of the pipes, break into the vent next to you and follow it to the far side and drop down.
Walk along the walkway and scope out the next section (break the boxes for shields).
Kill the Barnacles on the ceiling and the Bullsquid (new enemy).
Backtrack to a door on the left.
Climb down the ladder behind that door.
At the bottom, follow the path and exit through the door.
There is a health kit on the far right.
Jump into the water an be careful not to get sucked in.
Swim to the left and continue until you find a ladder.
Go up the ladder and use the health kit if you need it.
Go through the door and follow the path left.
Take the next door on the left and follow the path until you see crates hanging.
Climb the ladders on the right and get to the top of the room. You may want to save now since it is a long way down.
Jump on the right crate.
Jump from crate to crate until you are on the other side.
Take the hallway on the left and go through the door.
Follow the path and climb the ladder.
Go through the door, follow the hallways, and exit into the tunnel.
Follow the path and use the elevator.

Office Complex

When the doors open, grab the shield and health outside and watch the headcrabs come towards you and explode from the electric bolts.
Follow the right wall until you reach a vent.
Break the cover using your crowbar and take the vent right.
Drop down on the other side and go through the white door.
Use the switch to turn off the power.
Exit though the red doors by the scientist back to the hallway next to the elevator.
Head to the other side of the hallway and break through the window.
Head to the left and down the far hallway.
Break the boxes to continue along and after a headcrab you'll pick up a shotgun and see a guard.
Go over to the guard and take out the zombie scientist before it gets the guard.
The guard opens the gate and you can go in and grab more ammo and health.
Talk with the guard to get him to accompany you.
Head all the way back to after you jumped through the window and jump into the room full of water, but stay on the table.
Jump along the counter, onto the table next to the health kit, and to the counter on the other side.
Use the switch next to the cabinets to turn off the lights.
Break into the vent, watch out for the headcrabs, and climb to top.
Stay crouched and move under the fan to the other side.
Continue along the vents and break through the grating at the end.
Begin crawling to enter a hallway.
Walk towards the side with 2 red doors to rajoin your guard buddy.
Push the crates together and jump up to a ladder.
Jump into the vents and break into the next area.
Break the next grating, being careful of the crab behind you, and beware the turret.
If you choose, you can run to the far hallway and lure headcrabs to their doom.
The doorway to the left leads past some ammo and back to the guard.
Follow the hallway the headcrabs were in, up some stairs, and to another guard.
Have him follow you and continue into a narrow hallway.
Work with the guard to clear out all the enemies.
After you clear the area, take the left path (with respect from where you entered) past a few vending machines.
Walk around the dangling barnacle and up the stairs. You can have the scientist follow you if you want.
The top of the stairs has a turret so get to the second flight quickly to put a wall between you and it.
If you hug the wall under the turret it cannot hit you.
In the next hallway, take out the zombie walking towards you (might I suggest the lovely exploding box) and then quickly run to the other side to avoid the turret.
Take out the enemies along the hallway and exit through a door.
Continue along the path left of where the guard is standing (team up with him while you're at it) to an area with a bunch of stretchers and a zombie.
Break the boards blocking the doorway behind the stretchers and continue along the path.
Take out the zombies at the end of the hallway and use the lever next to the door.
Climb the ladder on the right and enter the vents.
Continue along the top, taking a right after the bullsquid breaks out from behind some boxes.
When you reach the end of the line, drop down, take a right, and go take down that bullsquid.
Afterwards, use the lever next to the rounded part of the wall.
Go back to the beginning and take the same path until you reach the end.
Wait for the right moment then walk onto the moving platform.
Break the boxes and grab the shields.
Wait until you line up and walk into the next part of the vents.
Follow the vents to an area with a bunch of bones lying around.
Take care of the barnacle in the middle then jump up to the top.
Enter the vents, again, and follow them until you can exit them.
Join forces with the guard and head up the stairs.
Watch the door in the shadows at the top of the stairs for another G man appearance.
Continue into the next hallway and take care of the 2 zombies.
Jump the gap in the elevator shaft and climb the ladders to the top.
Jump to the final ladder and climb on top of the elevator.
Break the grate and jump into the elevator.

We've Got Hostiles

Exit the elevator, go right, and use the kits on the left wall.
Break the glass next to the fire door (if you want) and run through it before it closes.
Run through the lasers and crouch behind a box as the lasers trigger the turrets.
Take care of the headcrabs that spawn.
Next to the marine's body you will pick up your next weapon.
Shoot the turret to knock it over and shut it down.
Continue along the path until more headcrabs spawn.
Take care of them then head through the next fire door just like the last one.
Jump over the blue laser, being careful not to cross it.
Continue on, crouching under the next one, and take out your alien buddies that spawn.
Use the health kit if you need it and continue through the hallways.
Jump over the red wire to avoid the turrets and take care of the aliens that spawn behind you before they trigger them.
Jump up using the green boxes and drop on the other side.
Quickly run to the door, break the glass, go through the door, and jump up the next boxes.
The next part has wet floors so go slow.
Start in the corner of the nearer laser.
Go diagonally (to hit the corner by the elevator) and jump the laser in the process.
Crouch under the higher side of the next laser (don't bump the turret).
Jump the next one and close the door and go through it.
Use the health pack if you need it.
Grab the ammo and energy packs.
Climb the ladder on the right wall and jump to the walkways.
Up the next ladder, across the bridge, and to the next area.
You now face marines, take care of any in this room then go down the stairs.
Use the health pack if you need to then press the button by the gate.
Walk onto the platform and press the button.
Jump off on the next level and clear the area of marines.
There are kits on the back right wall.
When ready, climb the stairs and enter the next area.
Navigate across the bridge (watching for the barnacles) and make a left.
Crouch under the two blue beams and navigate the red ones if you can, otherwise run through them, break the glass, and take the first left.
Take out the marines.
Use the barnacles to your advantage if you are low on health, they eat marines too.
After the room is clear, make your way up.
There is ammo and health at the end of the walkway.
At the top, go down a hallway to the next section.
Again, navigate the bridge, watching for the barnacles.
Continue to the next area and clear out the marines.
Once the area is clear, head down the walkway and to the back left of the bottom of the stairs.
Use the health kit and press the button.
Go in the elevator and go up.
At the top, hug the left wall to another health kit.
Use this room as a base and clear out the next area.
After one of the explosions, run out and about half way out go left and into a bunker with a ladder.
Climb to the bottom of the ladder.
Go left and use the kits if you need to.
Walk over to the cover on the vent and press the use key (E) to open it.
Stay inside while some marines repel past the opening.
If you want, take them out but watch for the grenades. More come down so don't worry too much about them.
Work your way slowly down until you can enter the vents (by the lower marine).
Go through the vents and drop down on the sides at the fan.
Enter the next vent and go all the way to your first left to drop into a room with some ammo, energy packs, and a health kit if you want to.
Climb down the ladder by the fan and enter the vents at the bottom.
Climb the ladder and go through the middle vent.
Use the packs in the area and press the button to open the door.
Follow the hallways to the next chapter.

Blast Pit

Break through the path ahead, it may take a while but your crowbar will get the job done.
Beyond the barricade, you will find headcrabs and a bull squid so be prepared.
Follow the right wall up a ramp to a control room
Flip the switch and check the door for your old friend Mr. Zombie.
Grab the grenades from the room and don't touch anything unless you want to explode.
Back in the previous room, climb down into the pit and get on the elevator.
Push the button as start going down.
At the bottom you will see a few health packs, a couple Houndeyes and a tram.
Take the Tram full speed until you see a pool of hazardous waste.
Quickly jump right, off the tram, onto the walkway by the wall.
If you have trouble jumping up, jump onto the highest part of the tram and then over to the wall.
Follow the right wall over to where the bullsquid is.
Climb the ladder onto the pipes and drop through a hole.
At the end of the pipe, you can jump up and see a bullsquid, kill it.
Jump onto the top of the pipe and follow the highest pipe.
Jump to the hallway at the end of the pipe.
You'll enter a room with a hazardous lake, walk across the pipe.
About half way, jump to the nearby pipe and climb up to the elevator.
At the top exit and watch the bullsquid eating the scientist to the right after the hallway.
Follow the catwalks and be sure to kill the enemies on the bridges without exploding the barrels.
Go across the bridge and through the door.
Flip the switch next to where you entered and continue on.
Be careful of the Barnacle on the ceiling and turn the switch next to the door at the end of the hallway.
Crouch through the room and continue, watching the ceilings for Barnacles.
Eventually you will see the tentacle monster attacking some guards, grab the grenades.
The monster only attacks based on sounds, so crouch and continue, using the grenades as distractions so you can move.
The path is fairly simple, follow the walkways and climb down ladders.
Do be careful of breaking boxes, I suggest breaking one then moving back until the monster forgets about the sound.
The first floor with a door has beams across it, crouch under them.
Go through the door at the end of the hallway and make your way across the bridge.
Break the non-explosive boxes for some health packs.
Continue along the hallway and make a right at the intersection.
Kill the zombies at the bottom of the ladder and go down.
Break the cover and climb sown the ladder.
Take the pipes and make a left at the intersection.
Climb the ladder at the end and kill the zombie.
Break the covering and climb up.
More grenades in the room on the left.
Continue through the next door.
Kill the zombies and climb down the ladders to a button at the bottom of the fan.
Press the button and book it back to the door you came from.
Do you trust me? Then jump into the fan.
Break your way into the vents and continue.
At the end of the vents you'll take a ladder down and see a zombie.
Kill it and enter the room.
Clear the room out and turn on the fuel and the oxy.
Climb the ladder and you're back where we started.
Head back to the room with the tentacle monster and continue downwards.
Toss a grenade to open the door and wait for your chance to leave.
Take a right and jump the gap.
Run to the next door to skip more gaps appearing.
Follow the path past a few houndeyes.
You'll enter a room with a bullsquid and some barnacles, there's a health station in the corner.
Head out onto the walkway and press the button to summon an elevator from above.
Get in and go down.
When the elevator stops, get ready.
Jump to the platform as you pass by and continue, there's another health station if you need it.
Continue down the hallway onto a platform.
Press the button and climb the ladder.
Watch out for randomly moving platforms and make your way up the next ladder.
Jump onto the center, press the button, jump across the middle, and press the button on the other side.
Climb back where you came from.
Elevator is out, you'll have to climb the ladder.
Go back to the central area, just run through the electrified water.
Head back to where the scientist got dominated by the tentacle and press the test fire button.
Don't stand too close to the window.
When the monster is dead, climb down into the hole it was in and fall into the water
Jump into the small room and grab the revolver.
Swim down and out on of the holes.
Go back up on the outside of the pipe.
Climb down the ladder and use the stations at the bottom.
Climb back up and follow the pipes.
Jump onto the large pipe and turn the valve.
Climb into the pipe, jump the gap, and follow the pipe.
In the next area, jump on the table to squish the crab and then break all the boxes for health and new stuff.

Power Up

Continue along the hallway to see a Gargantua.
He's big and he's mean. Run diagonally into the opposite tunnel.
Take the left path and watch for the falling portion.
Climb back up and break through the doors.
Talk with the dying security guard.
Head back down where the headcrabs were and continue along the hallways.
When you see a room with 2 Vortigaunts back up behind the wall as they explode.
Use the valve to enter the next area and climb to the top.
Kill the soldiers and toss a grenade in the left corner as you enter the next area.
Wait for the turret to power down and use the health station and continue.
Follow the hallway and use the explosive boxes to your advantage in the next area.
Down the ramp near the entrance to the room you'll find grenades and a health station.
Through the door are a ton of soldiers, but just walk on the ramp and kill the soldier that appears behind you.
You need to take the left hallway but there are soldiers on both sides.
When the area is clear, use the HEV station and go over to the elevator nearby.
Send it down empty once and notice all the traps and enemies that would set the traps off.
Go down the elevator, jump over the trap as you go down, and kill the enemies before they set off the traps.
Follow the hallways left and up a ramp.
Take the stairs down to the bottom and notice the fish swimming, they do bite.
Kill the zombie behind the wall and use your crowbar on the fish as they attack.
Break the boxes under the machine and head to the second floor.
There is a health pack on this floor and a panel with a button you need to press, unfortunately it is behind electric bolts.
Run in, turn the power on, and time your way back out.
Head back yo the elevator and take care of the guys coming down.
Go up the elevator and clear the floor.
Break some boxes for health packs if you need to.
Head all the way back to the room with the dying guard, you may want to save now.
Use the HEV station and draw the Gargantua to the window.
Head back to the door to the room with the Gargantua and run out and immediately left.
Run to the very end, up stairs on the left, and flip a switch on the right.
Exit through the small door by the stairs and head back to the large room.
The tracks are now active so jump over them or take shock damage.
Move the tram to the circle platform in the center of the room and flip the switch in the room with the dying guard.
Get back on the tram and ride it to the next area.

On a Rail

Jump off the tram, grab the health packs, and flip the switch.
Slowly approach the platform, notice there are barnacles on the ceiling.
When you drive onto the platform it automatically goes down.
Take the tram out of the water and just keep going.
You eventually come to a wire hanging from the ceiling, ride under it just position yourself so you won't hit it.
Beyond that wire you can see some enemies.
Take them out and slowly move forward until you can take out the turret in the room on the balcony.
Take the tracks straight and then hit the first junction switch to continue going straight.
Follow the tracks and kill the bullsquid and barnacles you come to.
Continue along the rails and kill another bullsquid.
Stop here and go up the stairs.
Break the boxes and flip the lever.
Head back to the tram and continue.
Go past the hanging wire again and this time take the left path.
After the level loading section, regain control of the tram and stop before entering the next room.
There are several soldiers in here, grab a decent weapon, like the revolver you got from the guard, and charge in crouching.
Take out the soldiers as you go up and move off the platform.
On your right is a red ladder with a health station at the bottom of it.
Continue on the tram slowly, going straight through the next junction.
Stop the train just before turning left and wait for the battle to end.
Inch forward and take out soldiers as you see them.
Jump on the big gun to finish off the rest of the enemies.
Take the stair by where the Vortigaunts were to find a HEV station.
Go back to the tram and take the stairs on that side.
Kill everything upstairs as you follow the right wall to a set of stairs.
Under those stairs is a box with a grate underneath that leads to supplies and a headcrab. I suggest taking it since it causes the enemies to battle each other.
Back at the bottom of the stairs, take the right path.
The boxes across the rails have supplies.
Follow the rails down the darker path, being careful not to fall into the tracks.
Head into the room at the end and kill the guards on the left wall.
Go through the door on the other side then back off while the opposing forces fight.
Behind the barricaded door you'll find a guard you can party up with.
In the room on the right you'll find boxes covering a health station and headcrabs.
At the end of the main hallway, you'll find a turret firing on you.
Use grenades and your secondary fire from the machine gun to kill the guy operating it.
Walk up to the Blast Doors to open them then back up and shoot the traps.
Climb down, kill the soldier, and head through the blast doors.
Explore the right wall for supplies and a HEV station.
Shoot the bullsquid at the end of the tunnel and take the tram through crouching.
Kill the other bullsquids as you pass them, but leave the turrets alone if you did not set them off.
You may want to save before rounding the corner.
After the second turn, there will be a rocket cannon firing on you, crouch down to avoid getting blasted to bits.
Let the tram take you past the first opening on the left and as you approach the second stop the tram.
Remain crouching and toss a grenade at the rocket cannon.
Shoot out the trap and continue along the tracks slowly, shooting traps as you come to them.
You'll eventually come to an area with Vortigaunts on the right side, kill them and get off the tram.
There is a health station in the room by the gate.
Follow the hallway to green boxes covering a stairwell.
Deal with the traps, get up the stairs, and clear out the enemies.
Flip the switch and use the HEV station.
Go back to the hallway and continue, jumping the tracks to reach the new tram.
Take the new tram to the end of the line.
Get off and crouch behind the mounted turret and take command.
The sandbags have a similar turret to when you partied with the guard by the soda machines, shoot the operator out of there.
Jump over to the ladder and run back as soldiers begin pouring in.
Clear out the soldiers then climb the ladder up.
Use the health staion on one wall and the switch on the other.
Back to the tram and on our way.
Take the platform up to the top and go past the electricity and slowly turn the corner so you can take out the traps.
Slowly go under the first conveyor of boxes and then stop the tram.
Toss a grenade towards the boxes (or if they broke the soldiers) by the gate.
Flip the switch by the soldiers and continue in your tram.
Crouch through the next box conveyors and as you turn the corner.
There is another rocket turret at the end of the hallway, stay crouched and stop when you see the ceiling turn.
Toss a grenade at the turret operator and continue.
Time your passage through the next section and take the straight path.
When the tram stops (it won't fall into the hole) take the nearby ladder down, after the game loads, drop a grenade and wait for it to explode.
Get into the room, but still above the red laser.
Jump off the ladder to avoid the laser and kill the zombies in the room with the health station.
Follow the tracks around a corner and save.
There is another sandbag turret at the end of the tunnel, hide behind the shorter box on the right wall and toss grenades at the turret. (you can stand up behind the shorter crate and not be seen)
Take the hallway to the right and listen to the green soldiers talking outside if you want, then take them out.
There is a sniper on the top left ridge, but if you just run for the blast doors you'll be fine.
Through the second blast doors, you will find yourself in a firefight of soldiers.
Go through the blast doors on the right and save, this part gets annoying.
Crouch up the stairs until you are past the second beam.
Jump on the right side of the stairs and jump over the last beam.
Save and go through the door.
Clear the area and push the red button in the second room on the right.
After the rocket has launched, head back to where the green soldiers were gossiping about you.
Go through the now open doors on the left and down the ladder.
Jump on the new fancy-pants tram and shove off.

Apprehension

Keep your hands and arms inside the tram at all times.
Free the barrels and climb the side stairs ofter the ordeal is over.
Jump across the barrels and you'll come upon a zombie eating a soldier, pretty creepy.
Take the stairs up and follow the path to the other side of the wall.
Alright, this is going to be a long swim so go fast.
At the bottom of the water is a blown open door to swim through.
Follow the path, not taking any side paths that requires doors or otherwise.
There is one section where you need to crouch to get through.
After coming out of the water, follow the hallway and meet your new nemesis.
Take care of the barnacles and follow the wall into a side stairwell.
You can swim under and watch this big fishie swim for a while, but bullets don't work underwater.
Follow the catwalk around the room and through a doorway.
Climb the ladder and listen to the doc's advice.
Use the stations on the wall and climb over the tank.
Drop into the cage and grab your crossbow.
Well how did you think you were getting out of the cage? Kill it and swim up for air.
Swim back down and notice the valve and gate by the machine, turn the valve, open the gate, and swim out.
Follow the path through the second door and clear the room of barnacles.
Go down the ramp and enter the red room.
Carefully take the catwalks around the room.
Try to stay in the center to prevent falling off.
If you do fall, find a ladder quick and get up.
You have to jump through the fencing, so save and pick a hole to jump through. Might I suggest the one without the electrical hazard?
Follow the underwater path until you can go up for air.
Climb the ladder and take care of the bullsquids.
Head down the hallway near where you came in.
Climb the stairs and use the panel to present your way across.
Rather than time jumps and have the game be difficult, push the nearby box off the balcony and slide it over so you can jump onto the boxes and climb the stairs.
Follow the yellow pathway to a room with a bunch of enemies and clear it out.
The scientist notices the monsters are dead and lets you in.
Use the panel by the B door and head in.
Take the path to the end and down a ladder in the back left corner.
Follow the hallways and head up the elevator.
Helpful advice from that guard there, continue down the hallway.
Say hello to the assassin. Keep your back against a safe wall and use your magnum as they show their faces.
Be sure that there are 3 dead bodies there before you let your guard down.
Feel free to explore and find the 2 health stations and the HEV station.
Go up the ramp and flip the lever that says SURFACE ACCESS.
After the doors are open, follow the hallways into a room.
Remember how annoying Metroid Prime is when you lose all your abilities and stuff? Well now you get to go through that again.
You are on a bit of a tight schedule, jump up using the boxes and crouching and grab the crowbar under the blue light.
Climb down on the side with a grating on the floor and follow the pipes.

Residue Processing

Take the path though a couple headcrabs and turn the valve at the bottom of the silo.
Quickly climb up and jump in before the water is too low.
Take the only path you have to a guard fighting headcrabs.
Climb up to the side of the tank in that room and jump across to the next ventilation path.
You'll come out and want to jump across to the next path but climb down and explore a bit.
Notice what obstacles lie ahead and use the health and HEV stations.
You can also get the dead guard's gun if you feel risky enough to navigate barnacles.
Head back where you came from and jump across the pistons through the next path.
Follow the left pipe until you can go no more and jump straight over to the other pipe.
There is a first aid kit on the floor and you can open a couple doors.
Jump across and into the next pipe.
Let the conveyor take you and drop you in the pool.
Swim down the ramp and jump out in the next room.
Continue swimming, crouching under the big spinning thing, and jump out in the next room.
Climb the stairs and open the door then come back.
Remember that room, but for now continue swimming.
Jump out to the right of the conveyors and go towards them.
Flip all the switches upwards and then go through the door on the other side.
Use the health station and then press the button facing the conveyors and hurry through the now stationary obstacles.
Let the conveyors take you and just time your way through any hazards.
When you enter a room with a ton of conveyors going every which way, simply follow the instructions below.
Drop down on a conveyor and let it take you to the next one to drop onto.
Speed through tunnels as one causes fire damage.
When you come to a conveyor that has 2 options, take the second conveyor, shoot the trap on the first belt, and then get on that one.
There is a trap after the corner beyond the first trap, throw a grenade to get it.
When you come to a room with giant rollers and 2 conveyors, jump across to dodge the rollers.
Continue on the right conveyor, but beware of where it drops you off.
Jump on the sides and time your way through it to the next conveyor.
Run along and leap of faith onto the ladder across the room.
Climb up and follow the path.

Questionable Ethics

Climb the ladder and kill the Houndeyes.
Shoot out the electric red things to open the way to the next area.
Notice the Gargantua in the tank, he doesn't like being starred at.
Two magnum shots will take care of him after he breaks out.
Find the red button, break the glass protecting it, and push it.
Follow the hallways, push the button in the room with the headcrabs caged if you want, and go until you find a security guard.
Bring your guard buddy along and go until you reach a room with a bunch of soldiers.
Clear that room and continue through the hallways.
There is another room you can push a button in, but the guard will likely not follow you can no one wants to kill the nice security guard.
Grab the weapons from inside the cages and continue, taking a right at the intersection.
Take care of the trap while hiding in the red room.
The baddies may come in, but just watch the door and you'll be fine.
When all is clear, take the newly opened path and follow it to a room with headcrabs on display.
After this exhibit goes horribly wrong, eradicate the problem and go up the stairs in this room.
Let the soldiers face off against the bullsquids and then finish off the victor.
Take every side path and set off a laser in a room at the end of each of them.
When all the lasers are one, activate the laser shield after you've pushed the box underneath it.
Exit through the hole in the wall and then through the doorway outside.
Pass through the next room and turn off the hazard so you can lead a scientist through it.
Lead the scientist to the main room and get him to use the scanner.
Go outside and clear the way to the right before sprinting into the tunnel and dodging the turret fire.
Follow the tunnel through the next doorway.

Surface Tension

Deal with the baddies outside and get ready for your first chopper battle.
Grab your newest weapon and hold the RIGHT MOUSE BUTTON to charge it. Aim at the chopper and 1 hit should do the trick depending on your difficulty.
Take out the foot soldiers after the chopper has been destroyed.
Charge your new weapon again and shoot out the bunker turret.
As you walk along the bridge, notice the ladder on the structure to the right.
Swim out, attempting to outrun the fish, and climb up.
Inside the top is a button for the turret and a health station.
Go kill the fishie with your crossbow.
Swim down along the dam and you'll notice a valve in the middle, turn it and go through one of the holes and under the fan.
Continue along the path until you come out of a pipe onto some sand.
On the left, you'll see some headcrabs getting shot at by a chopper.
Go straight and climb up a ladder on the left.
Jump over to grab health, shield, and ammo then back onto the ledge.
Follow the ledge to another ladder and climb up.
Walk along the left wall and take the second path.
Whenever you see the sand lump, it's a headcrab about to jump out.
As you make your way across, you'll get ambushed, Retreat to a safe place and take out the enemies.
Cross the area and enter through the door on the other side.
Turn the valve and head back to the previous area.
Take the path you came to first and you'll come to another tentacle.
Stay out of reach as the chopper makes sneaking difficult.
Follow the left wall and if you are like me and running out of patience destroy the chopper.
Follow the right wall (based on where you came in) and you should go behind a rock and down a slope.
Go up the hill and onto the rock.
You may just want to save and go for the storm drain, steadily shooting out mines as you find them and retry.
Shoot out a mine in front of the drain (practically touching the wire) and another in front of a tent on the left wall.
Follow the left wall, grab the supplies in the tent, and jump into the storm drain.
Break in and follow the pipes.
Slowly inch out of the tunnel and look right while doing so to take out enemies before they see you.
After you are out of the pipes, slowly move left and take out the guy below you.
Follow the path the guy ant turret are on and kill the guy in the cave at the end.
Crouch onto the ledge and kill the guy under the pipe.
Carefully slide down the pipe and move along the ledge on the right.
Be ready to kill the guy in the cave and then head to the back left of the cave to get a rocket launcher and another chopper to test it on.
Hide in the back of the cave until the chopper passes then shoot it while it is turning.
After the chopper is down, continue along the ledge and up a ladder.
Continue going upwards, crouching to not fall off when need be.
Head into the next storm drain and follow it to an intersection.
Take the right path, run through the water, into the next pipe, and follow the right path.
Slowly climb the ladder and take out enemies as you see them.
Climb out and run into the garage to find a health station(there is one in both garages).
Use it as you finish off the rest of the enemies.
Break the exploding crate (from a safe distance) and use the ammo to blow up the tank.
Follow the right wall to a button near a gate and push it.
Enter the next area but be careful of the rockets from around the corner.
Use your heavy weapons to deal with the tank and proceed.
You can either go straight or through the hole on the right, the hole leads to enemies, ammo, and supplies.
Follow the road into the next area.
Deal with the guys that drop in and take the right path.
Be careful of traps along the walls and watch for the sniper up along the right side.
Toss a grenade to deal with the minefield, or save and use your pistol through trial and error.
Before going under the barbed wire, toss a grenade in the hole in the wall behind it to deal with the sniper.
While under the barbed wire (and a safe distance away) blow up the barrels.
Climb up the fallen tower and follow the left vents to a hole in the roof
Drop into the boxes and head into the hallway.
You have to dodge these traps, destroying them means death.
After the second trap, head through the door on the left.
Go through the gap into the main room.
Kill the headcrabs before they blow up the place and head through the gap in the boxes near where you drop down.
Navigate the boxes, crowbarring through the large one with the crack.
After the dead guard, move the box on the platform surrounded by yellow and black stripes towards the middle of the room.
Head back towards the guard and follow the wall up some stairs.
Deal with the crab at the top before it is too late.
Jump the trap and press the button.
Go through the gap, onto the box, and over the traps to the middle platform.
Press the button and pick up your new weapon at the bottom.
Save the guard from the 3 soldiers, then enlist him as you follow the hallway.
There is a turret in the back of the truck so be careful as you pass.
Run up the ramp then turn directly around and run back down.
Wait until everything outside explodes.
There is now a tank and some soldiers outside, lure the soldiers in and deal with them one at a time.
Save.
You have to zigzag back and forth to dodge the tank's shots and get behind it.
Use grenades to finish it off.
Follow the left wall until it turns right, then watch the back wall for a turret.
Deal with it.
Follow the path through a door on the right and take care of the soldiers inside.
Go upstairs and befriend the guard into letting you into the storage room.
Have your 'kid in a candy store' moment and go back outside via the window upstairs.
Follow the ledge across to the ladder opposite where you entered the building.
Climb up and get ready.
Carefully climb down through the debris and deal with the soldiers as you see them.
From the second floor debris, jump through a doorway opposite where you came from.
As you exit the hallway a bunch of soldiers with fly in, hide in the room on the right.
Let the soldiers and aliens battle each other, then finish off the victor.
Get into the hangar opposite where you entered and deal with the turret and next enemies.
Follow the path under the turret and go get your soldier buddy and some ammo.
Have him follow you back towards the turret and open the door near it.
Use the stations inside and climb the stairs an man the turret.
Blast open the door in the landing area and then the guys that come out of the hanger.
Kill the vortigaunts as you round the corner and jump on the turret to keep the population down.
After they stop appearing, use the thing in the middle as a trampoline to get to the second level.
Deal with the guys beyond the wall, after they fight each other, then take a vent on the right.
Watch out for some guys in the vents, and keep moving.
After breaking a grating, back up a bit and clear the room.
Walk through the door then back inside as an exit presents itself.
Lower the car jack and press the button again an hurry onto it.
Deal with the soldiers, jump on the turret, and make your own exit.
Sit on the turret for a second to clear your exit.
Follow the path and you can witness a battle between the aliens and the soldiers.
Finish off the survivors and jump along the catwalks to the next area.
Take out the next alien you find then let the two forces fight each other.
Use the trampoline to jump to the room and break in through a grate into some water.
Jump out of the water and follow the tunnel.
Move back into the water after the soldier presents you with a problem and wait for the clear.
Take the pipe again and get revenge on the soldier at the end.
Watch the soldiers fight the headcrabs and finish off the winner then jump across near the ladder and turn the valve.
Head into the pipes and follow them to a stairwell.
Go up and team up with the guard.
Go downstairs and clear the room.
After the guard opens the door get him to follow you again.
Watch the soldier fight some vortigaunts then continue.
Get the guard into the room by the gate and he will open the door for you.
Follow the hallway and wait before going into the parking garage.
Draw the big guy nearer then use grenades and rockets to beat him.
Follow the path to the right and use the trampoline to jump over the wall into the water.
Walk along the pipes and use the lever on the left to move the target upwards.
Press the button to call an air strike at the cross section of the lines, opening the exit for you.
Blow a hole in the wall as well and bomb the tower to make a bridge to the exit.
Take your path and follow the tunnel to a lambda gate.
Exit through the nearby doorway and follow the hallway.

Forget About Freeman

Jump over the rail on the right.
After the first piece falls, jump onto the rail and over the piece into the hallway.
Follow the hallway through a room where they are talking about you.
Talk with the guard if you want and draw the guys in the next room back.
Jump back to the room where they were talking about you and flip a switch by the radio to deploy a turret.
Flip it back when the enemies are dealt with.
Flip it again and run for the next room.
When the enemies are dealt with, more spawn behind you, but the turret will get them.
Continue along the path, going right at the intersection.
Use the valve next to what I call the laser light ball and go downstairs.
The ball will likely drop those alien maggots you throw at people but this time they attack you, so be ready.
Wait a little bit and you'll hear the pest die.
At the bottom is a turret with a laser activation behind the ladder.
Deal with the headcrab before it trips the turret.
Enter the next area and jump to the middle platform.
Push the metal box into one of the waterways and use it to jump over the fencing.
At the end of the waterway, get out on the left and notice the big tank with another of your fishie friends in it.
Jump to the section on the left (it is shallow and the fish cannot get you there) and follow that path.
Crawl under the cog spinning and use your crowbar to deal with the leech guys.
Quickly navigate the pipes and go up for air after you get to the higher section.
Continue along the waterway and you'll see the tank with your fishie friend again, jump on in since there is a fence blocking him from your pool.
On the other side is a turret, some soldiers, and lasers to set off the turret. Deal with them as you will.
Grab the supplies and climb the ladder.
There are a couple soldiers and a tank at the top of the ladder, so hide behind the rocks and use your rockets on the tank after the soldiers are finished off.
Go through the door behind the tank and deal with the turret on the left.
Use the health station and go into the elevator.
At the bottom, jump over the hazardous wastes and to the left is a battery.
Take the right path and deal with the soldiers up the steps on the left.
You can grab some health and shield by going straight, afterwards go up the stairs.
In the next room, grab the turret on the tank and deal with the remaining enemies.
Use the tank by looking into it and pressing the use key (default E).
Deal with the guys that rush in and clear the room.
Break the boxes for supplies.
Out the door you blew open to the left is a turret, carefully take it down.
Take the path behind the turret through two doors.

Lambda Core

Press the button in the station and jump on the platform.
At the bottom are some headcrabs and a bullsquid.
Clear the area then climb the ladder, use the health station, and continue on.
After the second door you will enter a large room with more assassins, find a safe spot and take them out. (You may have to move into the room to draw them out)
Along the right side of the room, after defeating the 3 assassins, is a hallway blocked by boxes. Break them and go upstairs.
There may be an assassin waiting on the stairs so watch out.
Go strait across and through a doorway.
The left path leads to a health and HEV station.
Take the right path to an elevator and press the button on the wall.
Go to the left then run back to your hallway and defeat your enemies.
Pass through the doorway, beat the remaining guys, and go through the door in the back right.
Have the scientist use the other panel and leave the room.
On the left are health and HEV stations.
Either use the elevator or climb up the the upper level.
Go through the door on the right and grab the new weapon.
You can press the buttons and test it or just save the ammo.
Go down the hallway the opposite direction and down the elevator on the right.
Exit the elevator and you will enter a larger room with lots of enemies, clear the area.
If you take the hallway near the elevator to the right you will find a guard you can team with and supplies and a scientist.
Go to the lower level and take the blue hallway.
Clear out the room you come to and climb the ladder.
Follow the catwalks down a hallway to another room with headcrabs and vortigaunts.
Clear the room, flip the switch on the blue thing, and leave.
Go all the way back to the room after the elevator and take the yellow path (it may seem like it blocks itself but it doesn't).
Watch for barnacles on the ceiling and clear the room.
Climb the ladder and move slowly so you don't fall.
Deal with the new guy and continue through the door.
Turn the valve and continue along the path.
At the end is a room like with the blue path but this time there are barnacles and no vortigaunts.
Go back as if going to the room with the scientist but instead take a left (unless you want to fill up at the stations before going).
Clear the room then climb down to the water.
Swim along the tunnels to a large yellow thing.
On both sides, turn the valves and swim as the water rises.
Clear the upper level, using the water as a hiding place, and climb up.
Be careful of the lightning and continue climbing upwards.
Exit through the door at the top and follow the hallway.
Raid the supply room and climb the ladder in the elevator.
Jump to the upper level and feel free to raid that supply room.
Take the path left and in the first door on the right you'll find a guard and health station.
You are free to explore, but take the hallway all the way to the last door on the right, taking care of all the enemies as you go.
You will come to the room with the big yellow thing and a green orb and orange orb. Save.
This part gets tricky, so take a breath and go through the orange orb when the yellow platform is below the green one beyond the fence.
Jump into the middle ledge when the wall says PORT 02.
Look up and find the green orb and go through the middle when a platform is underneath it.
Duck under the pipe and go through PORT 04.
Go through PORT 07.
Get to the middle platforms and press the button on the outside walls on both sides.
Jump into the middle orb and go through the door.
Take the path left and up a ladder on the right.
Follow the hallway through a glass door.
Raid the supplies and wait for the scientist to open the door.
Play with your new ability then exit the room and use the stations.
You will enter a large room, walk to the other side and climb the ladder.
Wait for the scientist to open the portal and deal with the flying annoyances that come through.
Stay on your platform, do not drop onto the floor.
When the scientist says jump, do it.

Xen

Long jump the first platforms then time your way down the moving ones.
Be patient as you make your way to the ground.
Drop off the side onto a spike that juts off.
The purple lanterns will shock you if you get close, the water here heals you.
Crouch into the middle area and use the things that look like mushrooms (there are 3).
Go through the center area.

Gonarch's Lair

Grab your rockets after dealing with a couple headcrabs.
Shoot the big guy in his stomach.
Watch out for his charge attack and the baby headcrabs he makes.
Eventually he will charge off down a tunnel, follow him.
Be careful of the middle as you can fall through but he cannot.
Keep at the stomach and he will charge down the next tunnel.
Carefully drop down and drop underneath the webbing.
Take him out in the stomach and he will fall to your level.
After he is defeated, he will make a hole, drop into the water to regain your health.
Drop into the pulsating green orb.

Interloper

This part can get tricky, deal with the vortigaunts first.
On the back side of the hill is a cave with healing water in it, go there and make a save.
While you sit and get heath, read.
There are holes in the ground that will shoot you way into the air, guaranteeing death if you miss any platforms.
There is a teleporter you need to get to via the flying mantas.
Ok you are healed by now. Take the nearby pit in your cave, breaking the webbing to go down.
Follow the path through the goop and into another room.
Kill the headcrabs and wait on the center platform for the pillars to go down.
Continue on and deal with the barnacles and bullsquid in the next section.
Break through the webbing, past more goop, through more webbing, and wait for the pillar.
Stand on the pillar and let it push you to the top. Save.
Patiently drop along the platforms until you can jump on a manta and ride o the teleporter.
There is a tentacle to the right of the cave.
Go left and take out the enemies with your crossbow from a distance.
Exit through the tunnel on the left after getting out of the cave.
Carefully follow the tunnel then run back and jump in the little hole in the wall.
Kill the barnacles and use this water to heal as you fight the Gargantua.
Continue along the tunnel to another room.
You will take the path to the right but be careful as the rocks hide the back that there is a big hole.
When you reach the other side the tentacle monster comes up.
Take the path and remain on the top while you go across to the other tentacle.
After the bridge take a right.
Deal with the two guys and go through the teleporter.
Defeat as many enemies as you can before entering the room at the end of the hallway.
Take the lifts up, using both the platform and the top of the lift to reach the top.
Use the lift to get to the conveyor and then cross over to the other conveyor.
Let the conveyor drop you into the water then take out the welcoming party.
Walk onto the platform next to the pool you dropped to to go up.
Go against the conveyor and follow the path, dealing with the enemies in the next room.
Take one of the pillars to the top level and clear it out.
DO NOT BREAK ANY BARRELS!!
Continue along the path and jump over the barrels in the way.
In the seemingly dead end room, stand in the blue gas to heal then crouch through the red tunnels.
Carefully drop down and continue along the red tunnels.
At the end, drop down either side and fight your way to a safe spot.
After the first ramp, go straight and you will find another healing pod.
Use the spinning lifts to get to the top and jump into the teleporter.
Jump along the platforms through the spooky red teleporter.

Nihilanth

This guy is really big and he shoots teleporters that you should dodge using something as cover.
Use your rockets to break the orange crystals high on the walls.
Do remember to remain aiming at your target.
After the crystals are gone, open fire on the big guy until all the orange orbs around him are gone.
Use the trampolines to jump above him and shoot into his opened head.
I suggest using your newest weapon with a constant stream as you go up.
After he is defeated, watch the final cut scene and make a decision. (either go or wait they lead to different endings)