MAP22: Habitat (TNT: Evilution)

MAP22: Habitat is the twenty-second map of TNT: Evilution. It was designed by Christopher Buteau and uses the music track "AimShootKill" by Tom Mustaine.

Secrets

 * 1) Walk straight through the wall directly behind you at the start of the level to access a short hallway leading to a soul sphere.
 * 2) Picking up the soul sphere in secret 1 registers a second secret.
 * 3) After picking up the soul sphere in secret 2, the large crate in the starting area lowers for a short time, revealing a switch. Flip the switch before the crate raises again and a hole will open in the corner. Drop into the hole to get the BFG 9000.
 * 4) Walk through the falling nukage at the beginning of the level and a lift will take you down to a room where a chainsaw is visible. Open the northern green wall to access a brown tunnel system. When entering the tunnel, you will hear a door open. Return to the previous room and get the now-accessible chainsaw. The room the opens upon picking it up is tagged as secret.
 * 5) Once inside the tunnel, follow it to the east until you reach a fork. Go right, then left, and then straight through the next intersection. A wall will open up to the left just ahead of you. Go through this green hallway (A) and follow it to the end, where you'll arrive in the main tunnel system again. Once in the main tunnel, go right, and the wall in front of you will open. Continue through this second green hallway (B) until you see a narrow passage in the left wall. There are some health bonuses inside.
 * 6) Inside secret 5, there is one wall that stops just before reaching the floor. Walk straight through it. A lift with a red skull key (keycard in ZDoom) on it is inside; it is triggered by entering secret 5.
 * 7) On the opposite side of secret 5 is a third green hallway (C). If you entered hallway A, a connector will have opened between hallway C and a fourth green hallway (D). There are several armor bonuses and a yellow door in hallway D, though the connector itself is tagged as secret.
 * 8) Exit green hallway C through the eastern entrance. This opens another secret connector between hallways A and B.
 * 9) Behind the level exit is a red door. If you got the red skull key (keycard in ZDoom) in secret 6, open it and step through the teleporter to be taken to the bottom of the exit pit. Get the combat armor and go back through the teleporter, which triggers this secret.

Bugs
If the level is played on Nightmare! difficulty, or with the -respawn parameter set, respawned monsters will continuously activate the floor-lowering linedefs in the tunnels, which can cause Doom to crash as the result of exceeding the moving platforms limit.

Routes and tricks
It will take quite some time to complete this level under UV max rules, as all of the enemies and all nine secrets are spread throughout the entire map, which is quite large in size. You cannot leave any of the long, winding tunnels in the east unchecked, for all of them are filled with hellspawn, and some of the secrets are located there.

On the other hand, under UV speed and NM speed rules, this level is one of the easiest in Evilution to finish. As you take the normal path through the level, you raise an L-shaped platform in the giant slime pit; walking across its western end causes the western pillar to lower, leading to an elevator up into the final area of the level. However, due to the way the Doom engine works, the walkover linedef that lowers the pillar can be triggered before the platform is raised. Through this shortcut, the level can be completed in under 20 seconds. It is also very easy to finish this level under UV pacifist rules with this route, as you face very little opposition on your way to the exit, and the few monsters you encounter on this route (the Spectres at the top of the western elevator) are easy to avoid, as long as you awaken them by firing a shot with any weapon while waiting for the elevator to come down. This will cause them to move away from the location you arrive in, and then you can run past them to the exit. Consequently, all of the UV speed demos of this level are also UV pacifist runs.

It is difficult to successfully record a demo on this map with respawning monsters, especially NM100S demos, without the game crashing, as respawning monsters can cause the moving platforms limit to be exceeded (see Bugs.)

Records
The Compet-N records for the map are: