Part 20

When marines emerge from a doorway, let the first one trigger a tripmine. Use a double-barrel shotgun on any subsequent marines. Staying crouched prevents them from immediately firing.

After the fighting stops, equip your .357 Magnum and return to the doorway. Eliminate any marines near it with headshots.

Move to the left edge of the doorway and look down the passage to the right. Shoot the computer bank on the left wall until it breaks, then wait for it to emit a continuous stream of fire.

Run down the passage, jump over the fire stream, and hug the right wall to draw out any marines.

If marines approach, retreat to the bottom of the nearby stairs and watch for grenades. Finish off any marines who survive the flames with the assault rifle.

If a grenade destroys a vent grating over the stairs, shoot the three headcrabs that fall onto the stairs.

Return to the spot next to the fire stream. Quicksave and quickrestore to potentially trigger more marines to charge.

Jump over the flames and search the area to ensure all enemies are eliminated.

Jump back over the flames and break open crates past the stairs to find ammo, tripmines, and grenades.

Break open crates in the radio niche near the flames for more supplies.

Past the large room with radio equipment, find an HEV recharger and a health pack.

To proceed, set three tripmines: one on the wall right of the explosive crates near the start, another right of the doorway after going back up the ramps, and a third under a red light to the right of that doorway (this third one is less critical).

Use the lift's control panel to start its descent. Get on the lift with your assault rifle ready.

As the lift descends, shoot any houndeyes (creatures that can detonate explosives) on the walkway before they detonate the tripmines near the lift's base.

After the lift stops, move off it and wait for it to ascend.

Once all nearby houndeyes are dead, drop into the water and climb a ladder to the walkway.

Check for houndeyes again, then shoot explosive barrels visible down the walkway.

Wait near the barrels for more houndeyes to appear and eliminate them.

Go down the ramp and find the stairs.

Descend the stairs halfway, turn left, and use your pistol to kill a headcrab in the distance.

Continue to the bottom of the stairs and stop just before the water.

While on the last dry stair, move to where you can see the power generator machine in the watery area.

Turn on your flashlight and shoot the rightmost of the two wooden crates next to the generator with your pistol. This activates the generator.

Return to the stairs where you shot the headcrab.

Use the first aid station on the right wall if needed.

Enter the room with the power generator console and use the button panel to its left to activate its green light.

Turn around and time your movement to run past the electrical bolt that periodically shoots across the path.

You can use one of the fans to return to the upper floor, but it is difficult. Alternatively, go back to the top of the stairs and along the walkway to the lift.

As you approach the lift, it will start lowering with two marines. Let one see you, then immediately break line of sight. The marine should hit a tripmine, killing both.

If the tripmines do not kill both marines, be ready to finish them with the assault rifle. Alternatively, shoot the nearest low-set tripmine with your pistol as the lift stops lowering to kill both marines.

After the lift ascends, use the button panel on the other side of its walkway to summon it.

When the lift descends again, get on it.