When you enter the level, wait on the floor at first and kill the aliens that appear. Then use the jetpack to lift yourself up to the tunnel way up high - in fact it touches the ceiling. Proceed through the tunnel, killing any aliens that appear, then when you come to the room with the giant alien statue lower yourself down to the floor. In the middle are a Flamethrower, some Napalm for it, and some Armour. Collect them all, then make your way into the passage on the far right-hand side. In this tunnel are three facehuggers. Make your way to the end and then lower yourself down. On your right are a Smartgun and some Smart ammo. Collect them then turn the jetpack on to get yourself up into the next tunnel. From here, go either way and use the jetpack to get yourself up to the next level. If you go one way, you'll end up in a room with a lift, in another you'll need to head down a tunnel to get to said room. If you're in the latter, you can also pick up the Smart ammo (next to the hole that you emerged from) and Grenade Launcher (in the tunnel). Ride the lift up, then proceed down the tunnel, straight through the next room, through the door the other side and follow the corridor round up the stairs. In the next area, there's a hole in the floor. Lower yourself through this hole to enter the generator room. Make your way down onto the platform - there's a Medikit below the platform if you need it - and shoot the glass covering the switch to turn the power on. Jet your way back up to the main level, then continue along the corridor, then left up the stairs shortly after, along the tunnel and into the next room. Here, ride the lift up. You now arrive at a huge intersection. Step off the lift, then behind you to your right are a Minigun, a Medikit, and some Armour. Collect them, then head down the tunnel ahead of you. You need to go up either set of steps, enter each room and shoot the panel which is tucked away behind the part of the wall that sticks out. The other panel doesn't smash. Repeat for each substation (beware, two of them are guarded by Praetorians, so use the Minigun you collect earlier), and then return to the main area. Now, hold down the jetpack key and keep holding it, slipping through all the gaps you meet, until you enter a long, vertical tunnel, a bit like a chimneystack. Hold down the jetpack key still, and ignore the room that is placed halfway up it - keep on going up. When you reach the very top, there are two "ramps", one either side of you. Over one of them you should be able to see a tunnel. Head for that tunnel. There's a Praetorian or two in there, but just run straight past them. As you near the end of the tunnel, the evac ship crashes into the room below. Fall or lower yourself to the floor to end the level