(1) This is the level you've been saving all that smartgun ammunition for--the hardest in the game! If you finish without having your armor destroyed and some health depleted, you had a good run. You will be using primarily the smartgun in this level due to the large numbers in which the warriors will usually be encountered; even for singles and doubles, these warriors seem to dodge much better than any of their predecessors, making using the pulse rifle or shotgun (while at the same time escaping damage) possible but difficult. The level consists of a primary corridor with 7 rooms exiting off of it. Most of the "doors" leading to the rooms and secret areas on this level are walls that you can simply walk through. On the EASY and MEDIUM settings, you can exit with your ammunition levels in pretty good shape because there are plenty of powerups available and you have the luxury of backtracking to get them exactly when you need them. On HARD (for which this walkthrough is written), the risk of reviving entire hordes of enemies at one time limits your ability to explore the rooms to only slight variations of a straight-down-the-row order. Now for the level itself: enter and move forward to grenade a company synthetic that steps into the main corridor from a recess on your right, then deal similarly with 2 additional synthetics dead ahead. Back up to shoot the alien canisters in the first and third recesses on your left for a pair derm patches.
(2) Now face the second recess on your left. This canister contains nothing, but once removed allows access to the room directly ahead. Run forward into the open area of the room and back up rapidly, smartgun raised to deal with the 3 warriors that attack. Now face the left-hand alcove of this room. Approach the green veil (but don't enter!) to draw out 2 more warriors. Now enter this area. The green acid curtain will knock your armor down 5 points. However, if you dropped a warrior in the immediate vicinity, you will only take 1 point of damage if you run over the alien cadaver FIRST and then continue on through the acid curtain WHILE THE SCREEN IS STILL RED, indicating damage from the dead alien. Apparently, if you are already registering damage from the warrior's acid, the game does not detect the new, more potent acid encountered. The alien corpse does need to be pretty close to the curtain for this to work, however. Once through the curtain, rotate right and face a lone remaining warrior in this immediate area. Kill it and grab the powerups to be had: 4 derm patches, a shotgun, and night vision goggles. Now exit this alcove and go straight across the open part of the room into another, smaller alcove behind another acid curtain (use an alien cadaver for "protection" every time one is lying close enough to a curtain to make it possible). In this smaller area you will find a derm patch and pulse rifle magazine. Move through the acid curtain and turn right to arrive at the back of this room. Up here you will obtain 3 derm patches and some smartgun ammunition. As soon as you near this smartgun magazine, a new warrior materializes in the small alcove that held the pulse rifle magazine and derm patch. Move down toward the central open area of this room and deal with it; depending on your current ammo level, you may want to grab the smartgun magazine either before or after you kill this alien due to the rounding trick.
(3) Now exit this first room and turn left. You now want to enter the second recess on the right side of the primary corridor. This room boasts the densest population of warriors of any location in the entire game. Smartgun ready, run down to the bottom of the ramp into this room and then back up immediately. Since the smartgun bullets will go through the aliens to damage any enemies behind them, you want to draw as many aliens as possible into the line of fire at one time in order to conserve ammunition. The risk is in going too far forward and having a warrior sneak in behind you, thus blocking your retreat back up the ramp. This can prove fatal! Properly executed, this maneuver leaves you back at the top of the ramp looking down on a horde of disturbed warriors. Open fire immediately, concentrating on the warriors nearest you (and, therefore, most likely to reach you and inflict damage in spite of the smartgun barrage). On the EASY and MEDIUM difficulty settings, you can really see the "smart" bullets fly at all angles to take out the enemy--quite impressive! Having quelled the initial assault, proceed into this room carefully to deal with the 3 or 4 remaining warriors (assuming you did a good job of luring the rest of them out). There will be 10 in all. The carnage over, grab the 5 shotshells, pulse rifle magazine, smartgun magazine, and acid vest (a sight for sore eyes!).
(4) Now exit this room and stay left to what was the first recess on your right as you first started down the main hall. On the lift here that will take you down to this next room lie a pulse rifle magazine and a shotgun. Step on the lift and drop down. Beware, as between 1 and 3 of the 4 warriors in this room may have found their way to the lift and be waiting for you! The 2 warriors originally waiting on the ramp up to the main room here are unusually weak for some reason; only 4 shotgun blasts or 3 pulse rifle bursts will do one in. Kill them all and do the same to the fourth (and third, if you didn't meet it at the lift) warrior in the main room at the top of the ramp. En route you will find a pulse rifle magazine. In the main room ahead rests yet another pulse rifle magazine as well as 4 patches and 2 shotshells. Now face the long slide going down to your left. Choose the shotgun and let yourself slide down toward the end but, do NOT drop off! You want to lure 3 to 4 warriors to the bottom of the slide in front of you, using the shotgun to eliminate them. Be careful not to get so close that the warriors can hit you, and be aware that once in a while 1 or 2 of them will jump up on the slide to come after you! Wait until 2 are standing together at the bottom of the slide for a rare sight: you can see the shotgun inflicting damage upon 2 enemies at once. This can save ammunition, but increases the chances that a warrior will come up the slide after you. If you didn't need both shotshells in the room behind (and above) you, you can even shuffle your way back up to the room for them when this little operation is finished.
(5) This accomplished, drop down off the slide and into the next room to face right (although watch your motion tracker for a lone warrior that sometimes attacks from behind at this moment). [NOTE: In this particular room, very few enemies will be revived as you backtrack through these corridors, possibly because their large numbers in this very wide area would pose a near-impossible challenge. However, the warriors do not make their respective appearances in this room as consistently as in other areas of the game. I have provided the most common scenario here, but be constantly on the lookout for warriors in this room only to make sudden and unexpected appearances!]
(6) Move ahead. To your left just around the first corner is a secret room behind a wall you can walk through--a warrior comes out of it after you almost immediately. Beware, as 3 more warriors will come after you at this point from the surrounding corridors! Kill them first and then grab the med kit and smartgun magazine inside the room. Don't miss the infected human here, either--"Help me! Help me!" (or was that "Kill me! Kill me!"?). Make sure that you grab all ID tags that these poor fellows cough up upon expiring, as this is an important component of your mission. [BUG! Allow a chestburster to emerge from any infected human in this convoluted room and instead you will observe one of several bugs. Nothing at all may exit the host. Or, nothing visible may emerge, but you can see a blip on your motion tracker; shoot it, and a warrior may pop up and then immediately expire. Then again, you might find that a bouncing greenish rectangle bursts out; when you shoot it, it may turn into a warrior fully capable of assaulting you! In addition, blood occasionally continues to spray out of some of these already-chestbursted humans if you continue to shoot them, even though they are already dead.]
(7) Continue out of this room (another warrior will attack at about this time) and stay left. Just around the next corner and to your left is a secret passageway leading back in a large circle toward the slide you came down. It is just opposite another infected human requiring elimination. Enter by walking through the correct "wall" (a warrior here will attempt to stop you shortly). You will also be moving through several more "walls" before you exit this particular corridor. Another warrior will materialize behind you and attack at this point. After killing it, continue ahead down the secret passage. You'll encounter a pulse rifle clip near an infected human and, just a few steps ahead, a wide area in the passageway. Here lie an acid vest, adrenaline burst, and seismic charge. Prepare to deal with yet another warrior as you leave this wide spot in the road. Before you exit this passageway and re-enter the main corridor of this "room," you will encounter 3 more infected humans as well as 3 more warriors that enter this area from out in the main hall.
(8) When you exit this elongated secret, stay left. Continue ahead and past the entrance to the secret passage. You will encounter 2 derm patches (1 is in a small hard-to-spot alcove in the wall to your right) and 4 humans--infected humans. You will eventually arrive at a corridor leading off to your right and up to a lift. This is your exit from here back into the main hall, but (trust me) you don't want to leave just yet. There is one final secret area you will want to explore first. Continue past the corridor leading to the lift and stay right. Shortly before you arrive back at the slide (where some revived warriors may be waiting) there will be a shorter secret passage on your right (there is a small alcove here) behind another walk-through wall. Within the room you dead-end at await the auto-map (the last you will see in the game), a derm patch, a smartgun magazine, and a smartgun to use it in. There is 1 final infected human here that needs to be eliminated, and he will occasionally cough up a pulse rifle magazine instead of the usual ID tag upon dying.
(9) NOW you are ready to leave. Head back to the lift; a warrior will attack at the precise moment you exit this final secret area. Beware as you drop the lift (by simply walking up to it) as any warriors in nearby rooms that detected your presence will be lying in wait for you here. The best tactic is to back up with the smartgun ready and lead these troublemakers OFF the lift and into the hallway before killing them. Trapped down here, they will not present a problem in the near future. You may have to repeat this process 1 or 2 more times as not all the warriors running around nearby will end up on the lift when it drops down. If there is a good-sized group congregated here, seismic charges can be very effective and also save smartgun ammunition.
(10) Now shoot the 4 alien canisters sitting on the lift for 2 derm patches and go up on the (hopefully) alien-free lift to re-enter the main corridor. Turn right and you will see 3 alien canisters on a lift directly ahead. Shoot the canisters for a single derm patch and step onto the lift. Up you go, and on your right you will find a derm patch and night vision goggles.
(11) By now the lift has probably gone back down. Drop off the edge onto it (it won't hurt) and this time move straight forward (this would have been to your left as you originally stepped onto the lift). Activate the night vision goggles and enter this darkened room. Hug the wall on your right and move forward around the edge of the room until you go past the first (far right) corner and have the central pillar to your immediate left. Walk along the line on the ground here leading to the pillar and peek around the right side of the pillar. In a small alcove directly ahead you will see a warrior. Grenade it (don't shoot too close to the pillar) and do the same to the second warrior directly behind the first. That's it for this room--enemies vanquished! Now grab the goods. There are 4 lifts here, 1 in each quarter of this room, that drop down when you step on them. (The reason for tiptoeing around the edge of the room is that the 2 warriors here like to attack when you are stuck down in the bottom of one of the lifts.) Clockwise from the door, the lifts contain a pulse rifle clip (there is an ID tag lying on the ground here also), a med kit and shotshell, a smartgun magazine and shotshell, and a seismic charge and derm patch. In the alcove the warriors were hiding in you will find a grenade and pulse rifle magazine.
(12) Exit this room, drop back down onto the lift, and stay left. There may be some revived warriors here depending on how well you dealt with the aliens on the lift in that last, corridor-filled room. On your right before you reach 4 alien canisters is another lift, this one with a single derm-patch-laden canister lying on it. A warrior will attack as soon as you approach; kill it (use the shotgun or pulse rifle if you're feeling quick today). Now activate your second pair of night vision goggles and step onto the lift to meet another warrior lying in wait below. After dispatching it, stick to the wall on your right (just as you did in the last room) until you are halfway along the far wall (there is a switch right here, but DON'T touch it yet!). Now rotate left 90 degrees to face the opposite wall. There is an alcove here with 2 warriors in it (also quite similar to the last room). Grenade both, enter, and grab the grenade and 2 med kits inside this small room. Activate the switch here to power up the lift so you can make your exit in a few minutes. Now backtrack to that switch you passed up a moment ago. You are probably curious about the 8 columns in this room. Each bears a warrior at the top. The switch lowers the columns in tandem, but you can deal with it. In the corner to your right (as you face the switch) lies a hypo pack (and ID card) that are blocked from you by one of the columns. As the columns drop, you will need to accurately grenade the warrior on this particular column and dart into the corner for the hypo pack. Be careful as this warrior will jump down off the column before it reaches ground level, making hitting it tricky. You will also have to dodge the warrior on the other column closest to this corner. Done right, you can grab the hypo pack unscathed and use the pulse rifle (for Heaven's sake, don't waste that smartgun ammo!) to casually eliminate the group of warriors that surrounds you a split second later. Your invulnerability will last just about long enough to pulse rifle all the warriors clustered around you. There will still be 1 or 2 more warriors left in the far part of the room after you have dealt with the main throng. Finish them off and grab the shotshell and pulse rifle magazine that also came down on the columns. Make sure you got that ID tag by the hypo pack and ride the lift back up to exit.
(13) Stay right, dealing with any revived warriors that may have leaked into the area. A company synthetic will start sniping at you here as well. Kill him ("it"?). Now shoot the 4 alien canisters and step onto the lift they are resting on. Enter the room below carefully and with the smartgun armed. Three warriors will probably attack immediately. Back up and smartgun them. One or 2 may get stuck down in the acid pools here, affording you the opportunity to use the pulse rifle and save some smartgun ammunition. However, these warriors may hop up out of the pools almost as quickly as they dropped in, so keep your distance. Also, be careful on this narrow walkway as it is quite easy to drop off into the acid pools yourself. Now move forward. There is a single grenade nearby, so if you are pretty close to the 20-grenade maximum use a couple on the warriors in the room directly ahead. There will either be 2 or 3, depending on whether 1 of the warriors that attacked when you first entered this room came from here or from an area to your right. Once they are dead, turn your attention to the unexplored walkway at a T-crossing you just passed. If you killed 3 warriors in that last part of the room, then only 2 warriors (the last in this level!) lie in wait ahead; otherwise, you will have 3 to deal with. If you can spare any more grenades, use them; if not, the smartgun is your safest bet. Attempt to draw them out 1 at a time, due to the narrow confines of the walkway between the acid pools here and the ease with which you can fall in. This accomplished, backtrack to the room with the 2 warriors you grenaded. Within lie 3 clips for the 9mm pistol (pretty much useless this deep into the game), a med kit, and a pair of acid boots. Don the boots last (by backing into them) and dart out into the acid pools. The small pool on your left holds nothing, while the far left pool contains a flame thrower. The large, continuous pool on your right holds a flame thrower canister and ID tag. Pay attention to where the single step leading in and out of each pool is, and be careful not to overshoot upon exiting and land in another pool.
(14) This short run accomplished safely, leave the area by entering the unexplored part of this room via the T-junction. On your way out you will find another flame thrower canister and the grenade mentioned earlier.
(15) Drop down to the primary hallway (there may be a revived warrior awaiting you), turn left, and exit. You made it out alive! Ragged, maybe, but alive!