[9-11] E2M1: The Installation

Near the start, find a room with a barricade. Go to the bridge, walk halfway across, turn left, and hop into the water. Swim to the far corner of the area with the low ceiling and look up to find a tunnel. Swim up it to find Red Armor.

After getting the Gold Key, a door opens behind you. Jump into the water below the opening and follow the paths to a ramp. Climb the ramp into a secret area.

Return to the room where you found the Gold Key. On the right side (facing the back wall), there's a small ledge with a barely visible staircase. Climb the stairs (you may need to jump) and jump onto the ledge. Walk through the fake wall to find +100 Health.

Go to the Silver Key room. Head down the stairs into a room with a left path, a right path, and water in the middle. Jump into the water and swim to a grate on the floor. Shoot or chop the grate (you may need to use the DELETE key to look down) and enter the opening. Follow the path to another grate; hit it to open Secret 5 and proceed to a room with items and a teleporter.

In the room from Secret 4, if you hit the second grate, it will open another hidden room. If not, go back and hit it. This room contains Invincibility.

In the room with the large steel cage containing boxes, hit the switch on one side of the cage to access a small elevator. Walk past the elevator to the left and shoot the wall to reveal a room with Quad Damage.

At the top of the huge cage, find a section with wider bars you can squeeze through. Go to the bottom of the cage to find Yellow Armor.