E2M4: Deimos Lab (Doom)

E2M4: Deimos Lab is the fourth map of The Shores of Hell in Doom. It is arguably harder than some of the levels following it as well as the prior levels.

Walkthrough
Walk forward and enter the teleporter. Take the first left and continue west across two rivers of nukage. At the end of the hallway turn north, then west, then south and go through a big metal door to find a lift. Press the button to lower the lift, and ride up to get the blue keycard.

Return through the big metal door heading north. When the hallway ends, turn right and then quickly left. Continue north to come to the blue door. Go through to find the yellow keycard. Grab it quickly, as the ceiling is a crusher.

Go through the nearby yellow door and turn left. Follow the circular hallway and take the first right, going down a lift. Go around this lower hallway in either direction until you come to a green switch on the inner wall. Click the green switch to raise stairs, and go up. At the landing, there is another green switch. Click and go up; repeat at the second landing.

In the room at the top there is a raised square platform. Walk onto the platform to open a door back at the bottom of the stairs. Go down the stairs, go through the doorway you just opened, and teleport.

The hallway ahead features a scrolling graphic behind bars. Walk down the hallway to see the exit door, inaccessible across a pool of blood. Jump into the blood and run to the small alcove just to the lower left of the exit door. Click the skull switch on the south wall of the small alcove to raise a bridge across the blood. Take the teleporter in the north of the small alcove.

You are back to where you last teleported from. Walk out of the teleporter and then back into it to teleport again to the hallway with the scrolling graphic behind bars. Walk down the hallway and across the now-raised bridge to the exit door.

Secrets

 * 1) At the start, there is a slightly off-color wall opposite a blinking light. Go through this secret door to find a shotgun.
 * 2) At the far end of the large hall you teleport into from the start, there is a lift. Go up to find green armor and a computer map behind an array of tall pillars. Walk very close to the short red pillar to the east of the tall pillars (it has a skull on top). The tall pillars will lower, as well as the north wall behind them, releasing some monsters. To register the secret, walk into the small room to the north that the monsters came out of.
 * 3) After you cross the two rivers of nukage, take the first doorway to the right. A door ahead on your right will close. Shoot it (with an impact weapon) to reopen it. Go through to find a blur artifact and a chaingun.
 * 4) On the platform where you pick up the blue keycard, click the switch on the south wall to lower the half-high wall to the east. Follow the walkway, through a pair of crushers, until you see a radiation suit across a crooked, narrow bridge. Carefully cross the bridge to get the radiation suit, and then drop into the nukage pool to the south. In the southwest corner of this nukage pool is a platform with a berserk pack.
 * 5) From secret #4, follow the pathway at the southeast corner of the nukage pool. You will come to a circular nukage river. Hopefully, your radiation suit is still working. Turn left and go around the circular nukage river clockwise. (This direction is necessary to trigger the next door to open.) At the north end of the circular nukage river, a door has opened. Go through to find demons, spectres, a soul sphere, and another radiation suit.
 * 6) After going through the yellow door, turn left and follow the circular hallway (past the lift on the right) to a doorway on the left, going down some circular stairs. Go down the stairs into a room with a short wall on your left, overlooking a pool of lava, and five metal doors on your right. Go over the short wall and get onto a platform with two medikits.
 * 7) From secret #6, go across the pool of lava and down a short hallway. Push the wall at the end to raise it. Take the second right to find a room with armor bonuses, health bonuses, and other stuff. As you enter this room, the wall behind you will close.
 * 8) From secret #7, push the green-colored portion of the wall to raise a secret door. Go down the passageway and push the wall at the end to open it. Go through and take the second left. Go up some stairs, follow around, and go through a metal door to find yourself back in the room with five metal doors (see secret #6). Go through the right-most door. There is a compartment across a nukage pool with some barrels; explode them from a distance. At the back of this compartment is blue armor.
 * 9) After going through the yellow door, turn left and follow the circular hallway past the lift on the right and the doorway on the left. In the easternmost part of the hallway, the wall separates from the walkway. Drop down into the gap and push the wall to raise a secret door. Inside, find a plasma rifle and a teleporter to the raised square platform in the room at the top-center of the circular structure.
 * 10) After you get close enough to the exit door to touch it, turn around. Another section of bridge will rise, enabling access to a soul sphere.

Routes and tricks

 * Use the teleporter in secret #9 to avoid having to raise the three flights of stairs to the top-center of the circular structure.
 * When you click the skull switch to raise the bridge to the exit door, run quickly out to get on the bridge as it rises. This avoids having to re-teleport your way back.
 * In secret #3, if you run quickly enough, you can get through the door before it closes too far.

Records
The Compet-N records for the map are: