Back to Ultimate Doom
When you begin turn to the left, take out the Shotgun Guys and run up the stairs for the Green Armor. Pick up the Shotguns for the guys and run back down the stairs. Turn around and take out the Shotgun Guys hiding behind the small pedestals. On the side of the right pedestal is a Button that opens the door out to the courtyard. You can ignore that for now because we’ll be going out there later for one of the secrets.
Go through the passage to the north and into the next room. Take out all the Zombiemen and continue to the next room with the zig-zag path through the acid pool. Watch out for the Imps on top of the platform.
Take the exit to the south and open Secret 1 on the wall to the right just before the room leading to the level Exit. This passage leads to the courtyard where you can pick up the Blue Armor.
Head back and enter the room to the south. Take out the Zombiemen, Shotgun Guy and Imp. Walk into the room and then run back out to the zig-zag path. The platform where the Imps where standing has lowered. This is Secret 2.
Walk back through the zig-zag room to exit the room on the north side. Go back to Secret 2 and a lift will have lowered in the corner. Ride it up for Secret 3. Follow the passage and drop back down to the zig-zag room.
Head south to the exit, take out the final Imp and push the Button to Exit the level.