Part 14

Crouch-walk back into the shaft after climbing up the grating.

Approach the next opening on the right slowly with the pistol and flashlight to sneak-shoot the headcrab.

Go down the crab's shaft to a spot where you can see two marines below through an unbreakable grating. You can likely ignore them and gather ammo from the room past the shaft.

If you need to engage the marines, use a double-barrel shotgun blast through the nearest floor grate for the red-beret marine, then use the assault rifle on the other marine through the same grate when he's in sight.

Return to the main vent shaft, turn right, and find a left branch leading to a room with a first aid station, two armor batteries, and assault rifle clips.

Climb back into the shaft using the green crates and grating.

Go back to the fan room, move along the narrow ledge to drop to another ledge, and enter its adjoining vent shaft to reach section c1a3d briefly.

Find shotgun ammo on a ledge at the end of the shaft, then return to the fan room and drop to the floor to enter the shaft opening below.

At the end of the long shaft, climb a ladder and get off on the lower of two small platforms.

Use its vent shaft to reach the silo door control room. Press the big red button to open the silo door, pick up shotgun ammo, and exit the control room.

Use nearby first aid and HEV stations if needed, then go through the silo door to where the 'Blast Pit' chapter starts.

Go to the far left of the big barricade and shoot the bullsquid in the distance with the pistol.

Use the crowbar to break down the barricade.

Shoot the two headcrabs among the boxes past the barricade.

Move through the big doorway, watching for another headcrab.

Go up the ramp to the small control booth and slowly approach the metal door.

Back off quickly when you hear the zombie hitting the door to avoid being seen when it breaks.

Position yourself to toss a grenade through the doorway unseen, then back up before it detonates explosives, killing the zombie.

Check the room for grenades and a health pack.

Use the lever on the control booth's panel to bring up a big lift.

Use the ladder to climb down to the lower-floor area, get on the lift, and use its button panel to start it. Turn around to face the opposite way.

When the lift stops, move onto the walkway with health packs, turn right, and drop to the tracks next to the rail car.

Whack the houndeyes that run at you with your crowbar (or use the shotgun).

Jump onto the rail car and move against its control panel. Press the 'Use item' key to bring up the speed display, then press the 'Move forward' key several times to reach top speed.

Crouch down next to the control panel to avoid bullsquid spit.

When the speed display disappears, stand up and look ahead. If the car stops and throws you, move to the back of the rail car before it does.

When the car starts crashing through wooden warning markers, quickly back off to avoid being thrown off.

As soon as you hit the ground, run toward the car. Jump-crouch back onto it, then get on the two little side beams on its right side and jump-crouch from them onto the ledge.

Turn left and quickly crouch-walk along the narrow part of the ledge to reach a wider part.

Shoot the bullsquid on the other side from a spot where a large pipe obstructs its spit.

Go to the end of the ledge and drop to the bullsquid's floor.

Crouch-walk under a huge pipe, then climb the ladder on its other side.

Get onto the top of the pipe and carefully make your way along to a smaller side pipe with an open hatch.

Drop down into that pipe and move along it until section c1a4k loads.