Part 8

Descend the hallway ladder and shoot the vortigaunt (enemy that teleports) on the other side with the shotgun.

Shoot the headcrab (small, jumping alien creature) on the crate ahead with the pistol.

Quicksave (manual save point).

Walk backward toward the headcrab's crate; upon hearing a teleport-in sound, run forward around the corner to evade newly teleported vortigaunts.

Run past the ladder and around the next corner, then look back and dodge fire from two pursuing vortigaunts, defeating them with the shotgun.

Quicksave again.

Return to the hallway junction where the first two vortigaunts appeared.

Engage the third vortigaunt down the right branch: let it see you, then duck for cover (press the cover button to crouch behind walls or objects) and wait for it to approach, then defeat it with the shotgun.

Crouch-walk (move while staying low to the ground) down that hallway with the pistol to sneak-shoot a headcrab hiding behind the second wooden crate.

Note: Skipping the straight hallway at the junction avoids fighting more enemies for a room with a first aid station (health recovery item).

Approach the electrical hazard (dangerous electrical discharge) around the next corner.

Turn on your flashlight and look for a headcrab on the other side; try to lure it into the hazard or dodge its leap and shoot it with the pistol.

To cross the hazard, crouch-walk along its right edge until you hit rubble, then watch the electrical bolt; immediately after it passes, run past the hazard, staying right to avoid a dangling electrical wire.

Once across, turn on your flashlight and shoot a headcrab in the dark tunnel to the left before it reaches you.

Switch to the shotgun and crouch-walk down the right side of the dark tunnel until section ba_yard3b loads.

In the warehouse basement, quicksave.

Charge around the corner with the shotgun and double-barrel the vortigaunt.

Strafe left and crouch-walk forward until you see an explosive barrel; shoot it with the shotgun to defeat a vortigaunt and clear the way.

Quickly double-barrel the vortigaunt that teleports in near the barrel's former location.

To reach the vent shaft, bash the wooden boxes and push/pull the unbreakable box near the shaft opening.

Jump-crouch onto the box, then crouch-jump into the shaft.

Go up the slanting shaft to an undamaged shaft, then turn left and go up a ramp.

Approach the ramp's top slowly with the flashlight on; sneak-shoot a headcrab to the left with the pistol.

Turn right and find a bashable vent covering on the left wall; shoot a headcrab through it if possible.

Turn right past that crab and go to the next corner slowly, ready to sneak-shoot another crab to the right.

Walk very slowly to the drop-off point in the shaft to sneak-shoot a headcrab at the bottom, then drop down to reach section ba_yard3.

Bash the grate covering at the end of the vent shaft and drop to the floor.

Pull the barrel out of the doorway, then go left and down stairs to find a dead security guard with a vest, helmet, pistol, and two bullet clips; collect these items.

Go back up the stairs and crouch-walk up the left side, then over to a green crate.

Toss a C4 satchel bomb (explosive device) near the marines, then crouch-walk back down the stairs before detonating it.

Run up and grab their dropped guns, including an Mp5 assault rifle.

Push the green crate in front of the nearby door.

Go through the other door to find a wounded scientist.

Listen to the scientist's dialogue about Dr. Rosenberg and the escape plan.

Check the shelf on the left for two health packs (one inside a bashable box).

Push against the lockers on the other side of the room to open the middle one and reveal a box of .357 ammo; crouch-walk into the locker if needed to pick it up.

After the scientist dies, move toward the door you blocked with the green crate to get a marine to open it partway.

Let the marine see you, then quickly strafe left for cover.

Very carefully crouch-walk with the pistol to a position where you can shoot the marine without being shot back.