As soon as you enter the level, switch on your image intensifier. Be careful - sometimes an alien appears in the tunnel. Exit the tunnel, then enter the space on the left in the next room and hold the jetpack key. When you reach the top, head left up a small ramp and then down into the vent ahead. At the end, shoot the part of the grate you can see then hold forward, jetpack and crouch at once - you should just about squeeze through. Collect the Flamethrower and Medikit, then shoot the barrel blocking the doorway. Proceed through it and into the large hangar housing the enormous, rocket-shaped shuttle. Jet your way right up to the top and then enter the lift there. Follow the vent down then shoot the grate at the end. Be careful, this corridor is home to a lot of aliens. Get to the end alive, then enter the vent on the left and kill the alien that appears and then head right. Lower yourself down into the cryo-sleep quarters. Crawl under the door and turn left into the main corridor. Go down it a little, then on your left is some glass. Shoot it then enter the Medlab. In there is an operating table, then to the left of that is a switch encased in glass - shoot the glass to operate the switch. A door opens in the room that reveals a Smartgun. Collect it, then proceed out through the main door which has also opened. Head left then when the corridor splits take a right into the generator room. There are some stairs on the left - go up them to the next level. Here there is some Smart ammo and two switches encased in glass - shoot both. Now head back down to the next level and exit via the door that has opened (the one in front of you when you walk off the stairs). Follow the corridor round and proceed through the large door at the end. Go through the door on the left, then the next, then enter the large door here. Jump and crouch onto the table in the middle to collect the security pass, then exit the room. Again, go left through 2 more doors, then go straight across and through 2 more doors. Now head through the do on e left. Take a right and you'll enter the main control room. On the right is a door - walk through both it and the next one to enter the Mother module. Aliens may well appear and claw at the door, but don't worry - they can't get through. When Mother gets fully powered up, the level ends