Part 9

Help your guard kill headcrabs in the hallway leading from the turret room.

Reach section c1a2a, the Vortigaunt Office Area.

At the top of the steps, find a second guard, talk to him to have him join you, giving you a total of two guard followers.

Bash the nearest crate to find a bullet clip.

Approach the large red-rimmed doorway cautiously; a headcrab will drop down, so back up and let your guards shoot it.

Talk to your guards to leave them behind.

Go partway down the hallway to find a side room to the left containing an armor battery and health pack.

In the hall, face the flashing green EXIT sign, then slowly back up until nearby vortigaunts see you.

Quickly run forward into the side room and squeeze into the space behind the open door.

Watch for vortigaunts to try to come behind the door and double-barrel them with the shotgun when they do. Crouch down to avoid melee attacks. You may have to go out several times to lure more in.

After the vortigaunts are dead, get your two security guards following you again.

Go past the side room to the intersection area, then look to the left for a weak ceiling panel.

Move toward it, then quickly retreat when a headcrab falls through; let your guards shoot it.

Go to the lounge-like room ahead and repeat the process with its ceiling-hid headcrab.

Look through the lounge room's small doorway to see a vortigaunt; shoot it once with the pistol, then retreat and let your guards finish it off.

Around the corner is a small side office with a vortigaunt; let it blast its way through the office window, then go in and get bullets from the desk after your guards kill it.

Go down the hall to a well-lit area with two doors, one labeled D-AL 102.

Check for vortigaunts near the D-AL 102 door or in the room past it, then lure out the ceiling headcrab in the other room for your guards to shoot.

A first aid station is in that room.

In the D-AL 102 room, a barnacle guards another door with the same label; crowbar-whack it.

Enter the scientist's dark room to find a health pack on a desk. Turn on the room's lights using the wall switch near the scientist.

Return to the lounge and hop onto the couch in front of the "Maintenance Access" sign.

Look up and bash the weak ceiling tiles, then climb up the ladder.

Look into the autoturret's alcove to activate it, then quickly duck out of sight and use the switch on the metal control box to turn it off.

Get the shotgun ammo underneath it, then climb back down the ladder.

Find the short exit corridor to the left of the lounge with vending machines.

Toss a hand grenade to blow up the vortigaunt hiding behind the farthest machine.

Have the shotgun ready to blast other vorts in the area past the vending machines.

Kill the barnacle past the exit corridor with the crowbar.

Go up the first set of stairs, then very slowly move up the second set with your pistol out, as there are three headcrabs just past the top. Shoot them or toss a grenade.

In the next hallway, wait until a zombie is passing an explosive crate, then blast it with the shotgun. Finish it with a headshot (a shot that lands on the enemy's head, usually an instant kill) if needed.

Move slowly toward the corridor's left turn, as two vortigaunts are around the corner. Lob a grenade to bounce toward them.

If needed, round the corner and double-barrel survivors.

Reach section c1a2b, Optional Areas and Zombie Cafeteria.

While approaching the door, stay on the left side of the hall to avoid a headcrab on the vent shaft above.

Go through the door to an area with a security guard; do not have him join you yet.

Use the flashlight to locate a floor-level vent grating to the left of the door.

Bash the grating and move along the vent shaft until you reach a big fan room.

Climb the ladder and go to the fan blades; time your run across when the broken-off blade is on top.

Bash the floor grating past the fan, drop down, and move until you reach a wall grating.

Carefully shoot two headcrabs through the grating before bashing it.

Bash through another grate past them.

Walk along the top of a vent shaft, looking for another grate to bash and go through.

Past yet another grate is an open area with rusty metal beams to cross.

Cross along the left side, moving around the cable, or use other beams to go around the cable.

Headcrabs will break through a wall ahead and to the right; shoot any crabs that leap out, including those that fall below.

Toss a hand grenade into the crabs.