MAP02: Underhalls (Doom II)

MAP02: Underhalls is the second map of Doom II. It was designed by American McGee and uses the music track "The Healer Stalks". The level introduces two new things to the world of Doom -- the fast doors and the super shotgun.

Essentials
Travel across the river and go up the stairs. Open the door. Turn left in the small corridor and press the switch near its end. Return to the entrance room where a barricade to the east has lowered. Follow the tunnel until you reach a room with a house and an opening to the sky. Take the walkway to the end where there is an opening in the house. Use the run key to jump over the gap into the house. Climb the stairs, pick up the red keycard and make another return to the entrance room.

Go through the door that was entered before. Proceed to the other end of the corridor where there are red key bars. Open them and press the switch to lower the western blockade. As you explore the new tunnel, take the second branch to the right where there is a passageway, a barrel and a sergeant stuck in the wall.

Enter a room with two holes in the floor. Take the southwestern one. You will find yourself in a dark passage with a lot of barrels so watch your shots. Pick up the blue keycard in one end and go through the door in the other to proceed to a similar passage. Find your way to the blue door, open it and go up the stairs. There is another blue door approximately opposite. Enter it and press the exit switch.

Other points of interest
In the eastern tunnel, there is a fork to a UAC door. The computer room beyond holds an unprecedented weapon -- the super shotgun.

Secrets

 * 1) At the top of the staircase inside the house where the red keycard is found, open the western wall just south of the alcove in which the key rests. Behind the wall, there is a small room containing a few sergeants, a combat armor vest and a teleporter shortcut back to the start of the level. (sector 79)
 * Secret exit [ Xbox only ] : After obtaining the red keycard, drop down and enter the northeastern chamber that has opened. Walk up to the narrow stone wall in the northwest corner of the chamber and press on it to be taken to the Xbox-exclusive secret level, MAP33: Betray.

Bugs

 * There is a blind sergeant (thing 8) in the room behind the first door near the start of the map.
 * Behind the bars locked with the red key, sector 39 (the alcove of the western monitor) is not "closed" because linedef 312 (the southern border of the sector) originates along the body of linedef 491 (an adjacent wall southeast of the sector) rather than its endpoint. It results in a paper-thin wall at the southern end of the monitor.
 * At the southern end of the western tunnel, there is a sergeant (85) that is immobile due to being partially inside the southern wall. He may be gibbed freely by the barrel next to him. Similarly, the center of a barrel (69) in the northern dark passage has been placed into a wall, which causes problems in rendering; despite being exposed by half, the barrel is invisible from most angles.
 * The lower sides of linedefs 327, 328, 338 and 339 are all untextured, producing Hall of Mirrors effects. They form the short steps on the bottom of the two holes near the blue keycard.

Records
The Compet-N records for the map are: The data was last verified in its entirety on December 16, 2013.

Map data
* The vertex count without the effect of node building is 430.