Part 41

After dealing with the initial guard, check the area past him for health packs. Return to the base of the slanty beam and find a door to push open, leading back to the alley. The guard from across the alley will be present here.

You can return to the roof via the slanty beam or the initial method. The slanty beam is faster but riskier; quicksave and try again if you fall. Alternatively, crouch-walk from the beam to the roof.

Once back on the roof, position yourself near the top of the slanty beam. Look past it and to the right to see the top of a broken wall. Take a running jump to it, then drop onto the floor piece beyond. As an alternative, crouch-walk down the broken wall to the left of the slanty beam and jump to the floor piece. Move to the other end of this floor piece, walk along a small metal beam to another floor piece, and then take a running jump to the floor piece next to the required doorway.

Proceed down the short hall to another doorway. Stop near it to see large doors with red STOP signs on either side across the helipad area. Equip the hornet gun, quicksave, and fire 55 (or 130) altfire hornets at these doors. If you destroy them, quickrestore and try again. If successful, quicksave.

Keep the hornet gun equipped and run backward through the doorway. Back up toward the center of the helipad area until you hear an explosion behind you. Immediately run forward to the doorway you came from. Stop just past it, turn around, and quickly use altfire hornets to finish destroying the large doors.

As soon as the doors explode, turn and run down the hall, then drop onto the floor past the doorway. Run to the large slanty beam and use it to return to the roof. Stay on the roof and observe the osprey plane dropping off marines to fight alien grunts. Stay near the top of the slanty beam to avoid being shot by the marines.

Each time the osprey hovers to drop marines, quicksave. Hit it with altfire hornets until it starts circling again. To destroy it, quickrestore and hit it with almost enough altfire hornets to destroy it. Wait until it flies directly over your roof instead of hovering, then finish it off with the pistol when it's not directly overhead. Alternatively, wait until it flies by without dropping marines, then finish it off with altfire hornets.

After the osprey is destroyed, return to the helipad area. Watch out for an alien grunt in the hallway leading to the helipad; there might be another one even if your tripmine got one. Sneak-shoot it with hornets or the pistol.

Quickly shoot down any surviving marines, preferably from the hallway leading to the helipad with the hornet gun.

You can go through the large doors you blew up to reach section c2a5f, but it's advised to find another large doorway to the right. Go through it and down the ramp to a locked supply room door. Deal with any alien grunt nearby (unless the marines killed it) using RPG rockets.

Go past the grunt and locked door to a door you can open to return to the alley. The psychic guard will be there again. Enter the building on the left and go to the supreme supply room. Gather what you need, then have the security guard follow you to the other supply room's locked door. After he opens it, collect the items and use the first aid and HEV stations if needed. Retrieve your other security guard if he is still alive. Return to the second supply room, have that guard follow you, then proceed through the large doors you opened earlier to reach section c2a5f.

In section c2a5f, equip the hornet gun and go to the corner where the large hallway turns left. Around this corner, dozens of vortigaunts will teleport in. Do not run for the mounted gun; instead, move to where your security guard(s) can see the vorts and start shooting, then retreat to cover.

After your guard(s) are killed, stay at the corner and shoot hornets, ducking for cover when a vort charges up. Switch to the assault rifle or shotgun if any vorts get close. Cautiously move past the corner once the vorts appear dead, as some may still be present.