MAP15: Industrial Zone (Doom II)

MAP15: Industrial Zone is the fifteenth map of Doom II. It was designed by John Romero and uses the music track "Running From Evil". This map also has a secret exit switch that grants access to MAP31: Wolfenstein, the first of the two secret maps of Doom II.

Walkthrough
At the start of the level, go through the green door to the left and ride the elevator down by flipping the switch inside. Once you reach the bottom, step outside. From here, turn left and flip the switch directly in front of you. This causes the large stone rectangle to lower, revealing a walkway up to a combat armor vest (A) - it's a good idea to pick it up, due to the amount of hitscan monsters in this level. From here, follow the alley between the two buildings to the south, then turn southwest towards the tall dark brown iron building. At the far corner of this building is the start of a spiraling staircase leading to the top. Climb it and get the rocket launcher between the two green torches. Just west of this building is a small raised platform with a white teleport pad on it (B). Face it and run (by pressing shift, by default) towards it and you should land on the platform and go through the teleporter. You will be taken to a high ledge on the side of a nearby building. Run forward along this ledge but let go of the run key just before you reach the end. You should land on another ledge a bit further below on a third building (C; it is tricky to get from the first to the second ledge, as full-speed running will cause you to overshoot the second ledge, so it may require several tries to perfect). Flip the lion-faced switch in front of you, then drop inside the building. Take the teleporter on the floor, and upon reaching the other side, turn around and re-enter the teleporter you just emerged from. You'll arrive on top of some crates in the previous building, with a red keycard easily in reach (D). Drop down between the crates to get a berserk pack, then exit this building through either the teleporter or the elevator in the opposite corner.

Once you're back outside, ride the lift up to the red door (E; in the grey and brown brick building at the east end of the "town"). Follow the walkway to another teleporter and go through. You'll arrive in the large building in the center of the lava pit. From here, go right and flip the skull switch to lower the lift next to it. Ride up and continue along the path, turning left at the nearby entrance into the building. Drop in and pick up the BFG9000 (F). This triggers an enemy ambush, so be prepared. After dealing with the monsters, enter the green alcove directly in front of where you picked up the BFG. The wall inside will open, revealing the yellow keycard (G). After you get it, flip the skull switch on the pillar and proceed up the newly raised stairs.

Once back on the high walkway circling this building, follow it to the south side of the building. From here you will be able to drop down to the ground on the far side of the lava pit - drop down to the far ground and go through the yellow door in the southwest building. Inside is a small lava river with three exits. First, grab the radsuit in the north-leading exit, then head to the end of the south-leading tunnel and flip the switch. Return to the main room, where some stairs have risen. Follow them all the way to the top and flip the gargoyle-faced switch at the end to lower a lift leading up to the parapets at the top of this building. Follow the parapet east to another gargoyle-faced switch. Flip it, then return to the main room of this building again. There will be a lighted arrow on the floor and ceiling of the room pointing to one of the walls. Open the wall it points to to reveal the blue keycard (H).

From here, you may choose to exit to the secret level (see the secrets section for instructions on how to access the secret exit), or continue to the level's regular exit:

Return outside and follow the grassy ledge southeast to an iron "bridge" leading across the lava. Open the yellow bars midway through and enter the yellow door of the building at the far side. Once inside, walk straight ahead and the wall in front of you will lower (I). Follow the staircase up to another apparent "dead end"; once again, simply approach the wall and it will open like a door. Repeat this technique with the next wall, climb some more steps, and through one last wall at the top. Go through the blue door (J) and follow the barred path to the exit teleporter, dodging imps' fireballs along the way.

Secrets

 * 1) From the platform the red keycard was on, drop down to the east to get a berserk pack (K). Lower the tan crate to get back out. An alternate way to get this secret is to lower the stack of two medium-sized grey crates in the corner of the room by pressing its northern side, and then ride it up and over the larger tan crate. You cannot get the red keycard this way, however.
 * 2) Go through the teleporter in the room with the red keycard and then follow the ledge outside to a shaft in the wall. Drop down into it while pushing against the north wall, and you will land on another ledge. From there run down onto a platform holding a chaingun (L).
 * 3) After passing through the red door, follow the corridor along until you reach the part where it gets narrower. Instead of going through the narrow passage, turn to your left and open the wall to reveal a secret cave (M).
 * 4) Once inside the building locked by a yellow key, follow the lava river south to the end, and flip the switch there. This raises a staircase back in the previous area (N). Walk up the first section of these stairs, but before turning left to continue up, open the corner wall in front of you. This reveals a secret teleporter. Notice that due to an editing error, the secret area will not be triggered unless one walks on the teleport pad using no clipping. Otherwise, you'll go through the teleporter without causing the secret to register.
 * 5) At the end of the staircase mentioned in secret #4, ride the lift to the roof of the building. From the top of the lift, turn east and run as fast as you can through the opening in the parapet ahead. You should land on an elevated platform in the lava pit below. Flip the switch there. This opens a passage at the east end of the lava pit (N). Entering this secret opens the exit to the secret level (secret #11).
 * 6) Return to the roof of the building (O) and follow the balcony north. Quickly drop back down to the lowest floor of this building and follow the lava river north through a small tunnel to a timed lift. Ride it up to another portion of the building's roof.
 * 7) Inside the southeastern building requiring the yellow keycard, walk straight ahead to lower a lift. Follow the path a short ways and start running up the stairs when you reach them. You will hear several doors open. When you get to the top of the stairs and across the bridge, make a u-turn to the left, and run across into the alcove with the megasphere (P).
 * 8) See secret #7 (this area counts as two secrets).
 * 9) When you run across the bridge mentioned in secret #7, a wall opens behind you. Go back and drop into the hole behind it (Q).
 * 10) Take the teleporter in secret #9 to be taken to another secret area (R).
 * 11) Secret exit: Return to the building from secrets #4-9. Follow the lava river south again and enter the previously unopened tunnel leading to a teleport to the secret level, MAP31: Wolfenstein (S).

Bugs
Due to a map bug, Secret 4 cannot be triggered as found unless the player uses, making it impossible for the intermission screen to display more than 90% secrets found for this level without cheating.

Records
The Compet-N records for the map are: