(1) This is one of the niftier levels of the game, and not very difficult to survive--a welcome relief. Move out of the entrance room and pulse rifle the egg directly ahead. There is a corridor to your right: run up to it, then back up immediately to kill the warrior that suddenly emerges. You have very little room to work with here, so choose either a grenade or the smartgun to avoid taking undue damage while killing this alien in these close quarters (you will find more of each ammo type ahead).
(2) You can now proceed safely into the long, rectangular room ahead. Work your way carefully to the end of this room, killing the 8 eggs en route. The only tricky part is aiming accurately up or down as you go over the ridges here, since they cause you to point first up and then down as you traverse them. [BUG! A number of eggs on this level do not release a facehugger if they are activated and burst open. They simply collapse as if shot.] About halfway down the room, a single warrior will attack from ahead and to the right. To avoid aiming complications related to the ridges here, you should stand your ground and once again use either a pulse rifle grenade or the smartgun. As you move, you will find 2 derm patches, a pair of shotshells, 2 pulse rifle magazines, and a med kit. Your exit from this room will be blocked by 6 alien canisters; shoot them for as many derm patches.
(3) Carefully enter the corridor ahead, making sure that you immediately dispatch the egg on the right. Continue to the end of this long corridor, watching for 3 more eggs hidden in narrow wall recesses as you go. Two recesses also hold a pulse rifle magazine and a shotshell.
(4) You will encounter 10 eggs in the next room, but the alien you should kill first is the lone facehugger that is directly in front of you across the room as you enter. This facehugger emerges from a smaller room containing body armor and 1 grenade, but don't grab the armor yet just in case you accidentally release a facehugger that causes you damage or in case you take an acid hit from a bursting egg. Work your way carefully here, as it is easy to activate the eggs as you move along. When all eggs have been eliminated, grab the body armor and grenade as well as the other goods here: 2 clips, a shotshell, 2 derm patches, and a pulse rifle magazine (save this last item until after you have pulse rifled the 7 alien canisters blocking your exit; you get 7 derm patches for your trouble). Don't plan on backtracking for the armor or grenade, because the doorway closes behind you as soon as you leave this room.
(5) The next room will be similar, with 12 eggs that need to be destroyed. Pick your way carefully to avoid any unnecessary facehugger encounters! Within this room also lie a smartgun magazine, 2 shotshells, and a clip.
(6) Exit down the narrow corridor to the last part of this relatively easy level. You will be dealing with 8 warriors in this large room. You should grenade each of them (except the very last) in order to avoid their resurrection later on prior to your exit. The first will charge as soon as you turn the corner in the corridor and enter the room. Kill it, stay left, and activate the switch you dead-end at, being careful not to drop down into the egg chambers below. As soon as you trigger this switch, 2 warriors materialize in the corridor you just entered from. Move forward cautiously to activate them 1 at a time and grenade each when it emerges. Now return to this corridor and turn left down the catwalk dividing the 2 egg chamber sections. Stay as close to the exact center of this walkway as possible; when you reach the other end of this dividing walkway, 3 warriors will be waiting--you know how to deal with them. You will hear the sound of lifts rising as you go--you have just raised most of the eggs out of their respective egg chambers and into view. The reason for staying in the center of the walkway is to avoid activating the eggs and releasing their facehuggers; moving quickly but carefully forward without slowing will reduce the number of 'huggers that emerge. Directly ahead will be the still-sealed exit chamber at the end of a short corridor. Turn left past this area, and you will end at a second switch. Activate it and reverse route. As you return to the exit chamber area, 1 warrior emerges from it. Grenade it. Now use the pulse rifle to snipe down at all visible eggs (as well as any 'huggers you may have released from the eggs) from the surrounding walkway. First work your way toward that last switch you just activated, then back in the other direction. You will work your way in a large circle to the other end of the room, dispatching all visible eggs as you move, and ending at the first switch you activated. You are now ready to explore the egg chambers. There are 2 ramps, 1 on either side of the central walkway where you first entered this room, and each leading into 1 of the 2 egg chamber sections. Go down into the right section first, remembering to watch for any loose 'huggers wandering around down here! From left to right, there are 3 rows of egg chambers containing 5, 4, and 2 individual chambers, respectively. In the first row you will find a shotshell; there is also a clip and another shotshell resting on the divider between this and the next row of chambers. When you reach the end of the first row, turn around and enter the next row, heading back toward the ramp. The second chamber here (as you travel back toward the ramp) holds a seismic charge, but the third holds an egg in an unraised egg chamber. You will not be able to shoot the egg before the facehugger within detects your presence and emerges. You should select the flame thrower and drop in, firing as you go. Be careful as the threat of being 'hugged is high! As soon as you drop into this area, the chamber lift will rise; kill the 'hugger and move on. There is a single derm patch resting on the divider between this row of egg chambers and the next row. Make your exit back up the ramp and go down the other ramp into the left section of egg chambers. This has a configuration identical to, though reversed from, the other section: 3 rows containing 5, 4, and 2 egg chambers. At the end of the first row lies a single grenade; there is also a derm patch resting on the divider. As you head back down the second row (toward the ramp) you will find acid boots in the second chamber and a clip on the divider to your right.
(7) When you reach the end of the second row and reverse route to explore the third row, the first egg chamber of the pair here drops you down a long lift to a secret room. Lying here you will find a derm patch, pulse rifle, and shotshell. Activate the switch here and the central column will drop, allowing you access to an adrenaline burst and a smartgun magazine.
(8) Head back to the lift to go up and move toward the ramp to make your exit, being wary of any revived facehuggers along the way. As soon as you reach the bottom of the ramp, a final warrior emerges from the corridor you entered this room through and comes down after you. Use a grenade or the smartgun for a quick kill, then head up the slippery ramp. Make an immediate left, taking you down the central catwalk, and go straight into the exit chamber. [BUG! If you have trouble achieving 100% for ALIENS at the ASSESSMENT screen--even though you darn well killed everything in the level--allow 1 or 2 eggs to disgorge their contents and kill these facehuggers to top off your score. It appears that if you complete this level without releasing any facehuggers, you will not kill enough aliens for a perfect score!]