Doom/E2M2: Containment Area

Firstly, you can check the corner in the right at the edge of the entrance alcove for a security vest if you need it. The shotgun on the high crate you see in front of you can be obtained by throwing the switch next to the window on the left-hand wall. Kill the Imps as they appear. Make sure to fully explore this crate-filled area - you will need the extra shotgun shells and bullets, plus as a backup around the first left-hand corner you can grab a Berserk powerup which will serve you well in case you run out of ammo (and you don't have the Chainsaw yet). If you are reduce to fighting with your fists, make sure you retreat after each hit attempt as enemy melee attacks hurt, especially on Ultra-Violence.

Look at your map - you want to head to the bottom of the crate area. Down here, there are two entrances - one leads to an open room with four columns, the other into a tunnel coming off from that room. Once you're in there, dispatch the Imps and head to the one opposite the entrance. Hit the switch to open the door. Step onto the open floor beyond and it will raise up to form steps up to the lit crossroads up ahead. Kill all the Imps and Demons that initially appear. Once it looks clear, go right, then right again at the corner. Head across the two long rooms with the hurting floor down the middle (don't forget to pick up the goodies as you go). At the far end of the third one is a tunnel which leads to a small room containing a Backpack on a lit pedestal. Grab it, and a wall will close behind you - followed by the wall in front opening to reveal more Imps and Demons. Kill them all. You will notice that in the room beyond, where the enemies came out of, there is a differently-patterned wall section to the right. You can open this to reveal more enemies, but on the plus side the wall at the back of the room where the backpack was will open. There is another similar wall on the right-hand side of the room you just revealed; beyond this secret wall is a series of Imps, and a door which leads back into the four-pillared room.

Go back to the lit crossroads and go left this time. Take another left and you'll find a room with blood-coloured slime in it, and the yellow keycard beyond it on an unreachable ledge. Thankfully, you can follow the pattern of lights on the roof to reach it; as you step off the platform another will rise out of the slime. Once you've got the keycard, turn around and head to the odd section ahead - there are three circular bits with platform sections rising up and down below it. You can get in the first one and you'll find a secret tunnel which contains lots of health bonuses, and will take you to near the blue keycard door off from the four-pillared room. Beyond the other two are some more goodies. You can check around this area for several goodies including a cell pack for the plasma rifle (and BFG if you had it) and some combat armour.