E1M6: Central Processing (Doom)

E1M6: Central Processing is the sixth map of Knee-Deep in the Dead in Doom. It was designed by John Romero and uses the music track "On The Hunt". The par time is 3:00.

Walkthrough

 * Letters in italics refer to marked spots on the map. Sector numbers in boldface are secrets which count toward the end-of-level tally.

Essentials
Head north from the start area (A) and take the first walkway to the east. Follow the walkway into a large rectangular room and pick up the red keycard at the far end (B). As you enter this room, the entrance will close behind you, then reopen after 30 seconds. Go back to the walkway and follow it to the west, where you will find two red doors (C). Open either door and follow the tan passage around to a triangular pier, at the end of which is the blue key (D), overlooking a nukage pool. As you leave the tan passage to get the key, a trap opens behind you (E), releasing a Demon (I'm too young to die and Hey, not too rough), or an Imp and a Demon (Hurt me plenty), or two Imps and a Demon (Ultra-Violence and Nightmare!).

Now return to the start area and go through the gray door to the north, which leads to a dark computer room (F). Exit to the east and cross the walkway to the blue door (G). Beyond the blue door is a maze of tan passages and small slime pools. This maze can be navigated using the left-hand rule (turn left whenever you can, and turn right only when you have no choice). If you do so, you will eventually come to the switch at the extreme southern end of the maze (H), which opens a tall green door on the west side of the maze. Continue following the left-hand wall until you reach this door (I), and you will see the yellow key atop a short staircase (J), along with a backpack. As you reach the top of the staircase, a trap opens behind you (K), releasing a Spectre (ITYTD and HNTR), or two sergeants, an Imp, and three Spectres (HMP), or four sergeants, an Imp, a Demon, and three Spectres (UV and NM).

Return to the dark computer room and leave through any of the yellow doors to the north. You will reach a landing above a large nukage pool. Go down the stairs to the north, around the walkway, and up another staircase to a switch between two candelabras (L). This switch opens the large gray door to the west of the pool (M). Run across the nukage and through the doorway; the door closes behind you, but reopens after 30 seconds. Take either the left or right staircase downward into a blue computer room. In an alcove on the west wall, there is a switch (N) which opens part of the north wall, exposing the exit room (O). As you approach the switch, however, two large traps (P, Q) open on the west and south walls, and the staircases back to the nukage room are sealed off (though they open again after 30 seconds). The exit room itself is guarded by a Spectre (ITYTD and HNTR), or four Spectres (HMP), or seven Spectres (UV and NM).

Other points of interest
In the first room, the northeast wall of the large slime pool contains a narrow doorway (R) through which some barrels are visible. This small room holds a green armor, three medikits, three shell boxes, and one or more Imps. The Imps can easily be killed by shooting the barrels from the walkway.

As you take the red key, five traps will open in the walls of the room, releasing a crowd of monsters. This is especially dangerous if the door of the room is still sealed. With great care, it is possible to get the key without triggering the traps. Alternatively, pick up the chaingun and the bullet boxes first, open the traps, then run past the monsters to the entrance and hide around the corner (S); a monster-blocking linedef prevents anyone else from entering the tan area, so you cannot be surrounded. Note that all monsters in the traps are deaf, and in fact one sergeant in the western trap usually does not notice you as you run out.

As you approach the blue door, a trap opens in the south wall of the slime room behind you (T), revealing a sergeant (ITYTD and HNTR), or two sergeants, a Demon, and a Spectre (HMP), or two sergeants, three Demons, and a Spectre (UV and NM). The new alcove also contains a medikit and a radiation suit.

If you solve the maze using the route described above, you will approach the switch through a curving tan passage along the southeastern boundary of the map. This passage also includes a bullet box, a shell box, and a discolored panel with armor bonuses arranged nearby in the shape of an arrow (U). Activate the panel to reveal a computer map. (The small room is not needed for 100% secrets.)

Behind the outer columns in the large nukage pool are a stimpack, a box of bullets, a radiation suit, and a medikit (clockwise from northwest column).

Between the downward staircases leading to the blue computer room is an upward staircase, which leads to a balcony (V) containing a medikit and a bullet box.

When approaching the switch in the blue computer room, if you enter the alcove extremely slowly, you can trigger the traps (W) without closing the escape routes (X).

Secrets

 * 1) Across the nukage pool from the blue keycard is a dark doorway.  As you enter the passageway beyond, a platform will lower in front of you (sector 169).  Get on the platform and ride up to obtain a soul sphere (Y).  (You may want to visit the north corner of the pool first; an alcove there contains a radiation suit (Z).  After picking up the key, face northwest, run forward off the side of the pier, then make a hairpin turn to your right.)  To exit the pool, see secret #2 below.
 * 2) In the east corner of the same nukage pool is a platform (AA) with a medikit and a blue armor.  The adjoining staircase (sector 181) leads to a blur artifact, a light amplification visor, and two boxes of rockets.  Click the wall switch to open a one-way door back to the start point.
 * 3) A short passage (BB) connects the blue door room (activate the south wall of the trap) and the yellow key room (activate the south wall at the top of the stairs).  It contains a rocket launcher, a blur artifact, and a backpack (sector 190).  The blue key is required to exit this passage to the northeast, but if you have it, you can get the yellow key without entering the maze.
 * 4) Crossing between the two lowest steps in the yellow key room opens a blocked slime passage (CC) leading northward from the blue door room; this releases two Imps (ITYTD and HNTR), or three Imps (HMP), or five Imps (UV and NM).  The slime passage eventually reaches a hidden platform with two medikits, several large ammo pickups, and a backpack (sector 65).  You can then open the door to the north and jump down into a brown courtyard (DD) containing a soul sphere (guarded by seven sergeants on UV and NM).  The soul sphere is on a column which lowers as you approach it; the adjacent wall is a one-way door which leads to the northeast corner of the large nukage pool (EE).  Note that this route allows you to complete the level without picking up the yellow key, but once you have entered the courtyard, you are confined to the northern part of the level.

Bugs
In UV and NM, two Demons are stuck together near the radiation suit in front of secret #3 (see screen shot below). This leaves them very vulnerable to the nearby barrel, and traps another Demon and a Spectre behind them until one is killed. The latter two monsters can still pursue the player if approached from the south, however.

In UV and NM, a Spectre is embedded in the north wall of the exit room. Although he cannot move, he will attack if approached closely.

The following actions can trigger the blockmap bug:


 * Firing eastward or westward at the north edge of the slime walkway in the first room.
 * Entering the first room from the south (via secret #2).
 * After leaving the first maze room to the east, turning right to face the first Imp (ITYTD and HNTR) or the first two Imps (HMP, UV, and NM).
 * Leaving the dark computer room by the west door, passing the column at the top of the stairs, then firing eastward.

Slime trails may be visible in the following locations (see screen shots below):


 * On the western part of the walkway in the first room, looking east along the south edge.
 * Opening the blue door from the left side.
 * Looking back into the maze through the tall green door.
 * Looking into the brown courtyard (secret #4) from near the northeast corner of the large nukage pool. (Strangely, if you are actually in the courtyard, no bug seems to occur.)
 * Looking back into the south staircase from the blue computer room.

Demo files

 * [[Media:e1m6secr.lmp|No monsters, 100% secrets walkthrough]] (file info)
 * [[Media:e1m6wik1.lmp|100% kills, items, and secrets on ITYTD]] (file info)
 * [[Media:e1m6wik2.lmp|100% kills, items, and secrets on HTNR]] (file info)
 * [[Media:e1m6wik3.lmp|100% kills, items, and secrets on HMP]] (file info)
 * [[Media:e1m6wik4.lmp|100% kills, items, and secrets on UV]] (file info)

Routes and tricks
The door to the red key room closes and remains shut for thirty seconds after the player enters, this is to prevent the player escaping when the red key trap is sprung. To avoid this substantial loss of time it is possible to block the door using a monster, one of the two Sergeants near the door being the most obvious choice. Simply move within the Sergeants' sight, while remaining outside the door, and they will approach the player. When one of the two is under or nearly under the doorway, rush forward past the enemy and into the room. If all goes as planned the player will activate the door trigger line, the door will attempt to close, be obstructed by the Sergeant and return to an open position. The player can then grab the red key and escape through the open door.

You may bypass the maze as follows: As you approach the blue door, the platform at the south side of the nukage pool will lower. Go through that area and through the two secret doors in the opposite direction from the above to get the yellow keycard. If desired, go down and back up the stairs leading toward the maze to trigger open the door to the secret passage in the northeast of the nukage. However, you can avoid using this passage by just going back to the central area and going through any one of the yellow doors.

You can also lock yourself out of the big room before the exit where you have to fight loads of creatures. First run into the alcove to trigger the doors hiding the critters to open. Take out all of them. The entrances to this room will open. Run out of the entrance to this big room. After a while the door will close. You will be locked out of the room, and cannot open the door.

Current records
The Compet-N records for the map are:

Inspiration and development
Early versions of this map appeared as E1M5 of Doom 0.4 and E1M9 of Doom 0.5.