Part 12

As you approach the teleport-in point, check the area for a first aid station and two bullet clips next to a dead security guard.

Equip your shotgun, quicksave, and jump over the red laser alert beam. Turn to face the two nearby explosive barrels. Blast them with the shotgun as a vortigaunt teleports in next to them to kill it. A double-barrel blast will kill the second vortigaunt that appears. Alternatively, jump over the laser alert's right end and run right to avoid the first vortigaunt.

Sneak-shoot the two nearby turrets. Bash the two large wooden crates next to each other to see one turret past them. Shoot its leg with the pistol until it goes down. For the other turret, go around to the right side of the green crate stacks, bash the wooden crate there, and shoot the turret leg you can see past it.

Hop to the top of the biggest green crate stack using a jump-crouch maneuver. Drop down past the stacks, run through the fire door, and jump onto the green crate stack past it. Drop into the next area (section c1a3d) quickly to avoid teleport-in headcrabs.

Crouch-walk on the wet floor until you see the nearest of the two turrets around the corner. Shoot its leg until it falls over. Repeat with the second turret near the fire door's glass-covered button, moving slowly and carefully. Alternatively, use hand grenades or charge with the shotgun.

After both turrets are down, check past the fire door for unexploded tripmines along the left wall. Shoot the nearest one with the pistol. Go through the fire door to find a first aid station and boxes for supplies. Climb a ladder to a walkway with more boxes.

After going up another ladder, equip your assault rifle and move along the walkway until you can look down into a room with a hostile marine. Open fire immediately. If damaged, return to the previous room for health and armor.

Go to the lower floor, find an aid station and assault rifle clips on a green crate (and a rifle next to the dead marine). Press the button left of the large lift to open it. You can have a scientist follow you and then slam the lift doors shut on him. Ride the lift up (section c1a3a loads).

Stay back as a scientist runs forward and is shot by three marines. Stay in the lift with the assault rifle out and shoot any marines on the upper walkway. Find the dark passageway to the left as you exit the lift. Dodge grenades and shoot marines with the assault rifle.

The marines may enter the side area with you. Try to kill the marine on the upper walkway with the pistol. Wait near the side area's entrance with the shotgun out for a marine to get near explosive barrels. Blow them up, then use the assault rifle on survivors.

After all three marines are down, search the area for supplies in wooden crates. Use the first aid and HEV stations near the back right corner if needed, or collect leftover supplies from previous areas. Find the stairs to the upper walkway, go through the fire door, and cross the bridge, watching for barnacle tongues. Kill barnacles with the assault rifle if they are difficult to avoid.

Optional Shortcut: Use the barnacle closest to the bridge above you. Quicksave, let it grab you, hit it with the crowbar, and use the "Move forward" key to land on the bridge. Turn left and proceed to a walkway above the room with the exit lift. Kill marines below and skip to the paragraph before section c1a3b.

Past the barnacle bridge, go down the ramp to the right to find a large area with crates, barnacles, and a conveyor belt. There is a higher floor with crates and marines. Toss grenades onto the higher floor.