Part 9

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

Proceed up the stairs to reach section c1a2a, the Vortigaunt Office Area.

At the top of the steps, find a second guard shooting headcrabs. Talk to him to have him join you, giving you two guard followers.

Bash the nearest crate for a bullet clip.

Approach the large red-rimmed doorway cautiously. A headcrab will drop from a weak ceiling panel; back up and let your guards handle it.

Talk to your guards to have them wait behind you, out of sight of the hallway.

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

In the hall, turn towards the flashing green EXIT sign and slowly back up until vortigaunts spot you.

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

Watch for vortigaunts to try and come behind the door and use your shotgun on them. Crouch to avoid melee attacks and go out to lure more in if necessary.

After all vortigaunts are dead, return to your two security guards and have them follow you again.

Go past the side room to an intersection area. Look left for a weak ceiling panel, move toward it, and retreat when a headcrab falls. Let your guards shoot it.

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

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

Around the corner is a small side office with a vortigaunt. Let it break through the office window, then enter to 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.

Lure out the ceiling headcrab in the other room for your guards to shoot. A first aid station is available in this room.

In the D-AL 102 room, approach the door guarded by a barnacle. Use your crowbar to whack it, then enter the scientist's dark room to find a health pack on a desk.

Use the wall switch near the scientist to turn on the room's lights.

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 the ladder.

Look into the autoturret's alcove to activate it, then quickly duck out of sight.

Use the switch on the metal control box to turn off the autoturret. Get shotgun ammo from underneath it.

Climb back down the ladder to the lounge.

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 your shotgun ready to blast other vortigaunts in the area past the vending machines.

If you have any security guards left, you can whack them for ammo or let them stay with you.

Kill the barnacle past the exit corridor with your 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 for the zombie to pass the explosive crate, then blast it with your shotgun. If it survives, give it a close-up headshot (a shot that lands on the enemy's head, usually an instant kill).

Move slowly toward the corridor's left turn, as two vortigaunts are around the corner. Lob a grenade to bounce toward them. If they survive, round the corner and use your double-barrel shotgun.

Move past them to 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 your flashlight to locate a floor-level vent grating to the left of the door you entered.

Bash the grating and move along the vent shaft until you reach a large 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 in a hallway, 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, carefully moving around the cable, or go around the cable using other beams.

When crossing, headcrabs will break through a wall ahead and to the right. Quickly shoot any crabs that leap out, including those that fall below.

Toss a hand grenade into the remaining crabs.