

It's locked right now, but we'll be back here for a secret later on. Before going through this maintenance door that the Possessed way lying against, take note of the door to the right. Take the Yellow Keycard from the body at the end of the hallway. Proceed along the catwalk and look for a Field Drone along the way choose another weapon upgrade. Defeat them all, then ride the elevator on the bottom level up (call it with the console). First defeat the few Possessed, then destroy the net, spwaning a lot of demons as usual. Continue through the other hallway to reach a large room with a Gore Nest in the middle. except that it requires the yellow keycard too. In any case, drop down to find the security station. The same applies when you reach the higher ground. When moving over the crate transportation system, do NOT stand still or you'll be torn apart by the lasers (a crate will bump you into it). The second way is to go right and move into the ventilation shaft.

One way is to climb the two crates to reach higher ground. The door in the far left corner of the room requires the yellow key card, so we'll have to find this first. Defeat them by staying on the move and using your shotgun effectively. There are various demons roaming the next area behind the door. The room also has a Health Station, which fully restores your health should you need it. Use it sparingly, and never on weak foes like Possessed and Imps. Any unprotected flesh will be instantly sewn through. You can switch with Square (or X on Xbox) to regular weapons and the chainsaw. This is a powerful melee weapon that can and will come in handy whenever you're with your back against the wall, or simply when facing a very powerful opponent that's about to shred you to bits. In this room, definitely grab the Chainsaw from the corpse. You'll find a few extra items this way, until you drop down in a room up ahead (which is also accessible by the door close to where you found the Data Log). The console to your left can be used to stop the elevators on the far side of the area, which you can then jump on to reach higher ground (you'll cling onto the catwalk). On the other side of the area, check out the workbench to find a Data Log. Defeat them all to continue try standing behind crates to avoid incoming projectiles and stay on the move otherwise. Proceed through the hallway to reach a large room with many demons inside, Possessed and Imps. These are essentially walking bombs shooting them will detonate their explosives, causing harm to anything standing close by, so be warned. To continue, pull open the jammed door and immediately shoot the Possessed Engineer waking towards you. Defeat the Possessed Soldiers inside to unlock this classic map. Now jump up to the highest walkway, where you'll find the lever to open the door.

Move to the end of this catwalk, carefully jump on the railing and from here to the platform nearby. To open it, head back to the large metal crate and climb it, then continue towards the armor. The door you see here (to the left) leads to another Classic Map. Defeat them and collect the health pickups if you need to. Take note of the crate in the corner we'll climb it in a second for a secret, but first, continue a few steps forward to spawn several Imps. Continue down the path and defeat one or two remaining Possessed.

Head back to the big room where you pulled the door open and click on the panel, then hop down. Go back to the hall and interact with the AutoMap Station. Your browser does not support the video tag. Going to the point of the armor also counts as finding a secret. Follow it to the end and check out the tunnel to find some armor. Turn around and check out the maintenance catwalk above the stairs you can jump towards it. At the end, use the computer to turn back power to the facility. Move through the hall, defeat the Possessed (try doing the first two challenges) and pull open the door on the left.
