Starting location[edit]
You start in the north-west corner of the map, and the exit is just beside you. You need the red keycard to unlock it, and it is just out of visibility.
You will first need to get the yellow keycard, behind the pillar in the south west corner of the room. Head to the north-easy corner of the room, and open the door using the switch.
In the twin rooms, defeat or evade all enemies, go through the corridor, and cross the second of the twins. Pass through the yellow key door.
Blue Key[edit]
Pass the yellow key door, and continue through the corridors until you reach the large room in the south-east. There are seveal monsters here that will attack from the corners, and will need to be elimianted. Try to remove as many monsters as possible, as you will need a radiation suit for a portion of this map.
First, collect a radiation suit, and take the north-east lift. Run across and collect the blue key card at the end of the corridor. On the return trip to the large room, the crushing ceiling has activated. Run through it as it is raising.
Red Key[edit]
Save your game at this point, because it is possible to enter an unwinnable situation. This will not be the case in Co-op play, as the lifts act as teleporters across the damaging area.
Head to the left of the large room, and press the switch to raise the barriers. Ride the lift, and run down the hallway. If you run at full speed, the crushers should be easier to pass on the return trip. Defeat all monsters, and head up the stairs to the northwest. The next room will be a pillar maze, most easily navigated by remaining close to the southern wall. Press the switch at the end of the maze to open the door to a circular corridor.
The final room will have the red key in view. Collecting it will unleash up to five arachnotrons, or one spider mastermind depending on difficulty. It will also open various monster closets throughout the level.
With the red key, head back to the starting location, either by the normal route, or the secret shortcut. The exit is located at the north-west corner of the first room.
Secrets[edit]
- In the room with the blue key blockade, run across the north-west crushing area. This leads to light amplification goggles, and a short-cut back to the starting area.
- In the room with the blue key blockade, use the lift to reach the south-west crushing area. Shoot the center of the far wall to reveal a rocket launcher to the right.
- In the room with the blue key blockade, use the lift to reach the south-east crushing area (or use the north-easy lift, which also gives line-of-sight). Shoot the center of the far south wall to reveal a switch to the south-east. This lowers the floor in the route leading to the red key, revealing monsters and a soul sphere.
- This secret is only reachable once a player got past the yellow key gate and enters the eastern corridor. In single player, this requires either the red key, or using the secret shortcut described above. In the north east twin-rooms, there is a small corridor between these two rooms. Starting from the north end of the corridor, run south, and go through the door. You should see a platform has lowered; quickly climb it. Approach the crusher and attack the guard that appears from behind. Jump across the gap, and enter the alcove ahead of you. This lowers the floor, triggering the secret. You can collect any additional items, including a backpack (plasma gun on easy) if you take the second lift on the right.