MAP15: Decomposition (Community Chest 4)


Community Chest 4 maps 12-20

01 02 03 04 05 06 07 08 09 10 11
(12 - 20)
21 22 23 24 25 26 27 28 29 30
Secret maps: 31 32
Bonus map: 35

This level occupies the map slot MAP15. For other maps which occupy this slot, see Category:MAP15.

MAP15: Decomposition is the fifteenth level of Community Chest 4. It was designed by Lord Z and uses a MIDI rendition of Metallica's "Creeping Death" sequenced by King Diamond (no relation to the musician). This map contains a secret exit leading to MAP31: Mortar Combat.


Map of Decomposition
Letters in italics refer to marked spots on the map. Sector, thing, and linedef numbers in boldface are secrets which count toward the end-of-level tally.


Start and Yellow Key

You begin at one end of a tan hall. Grab the shotgun and box of shotgun shells. There are three zombiemen and two shotgun guys behind the pillars here, so wake them up and clear them out. As you follow the hall east, you will encounter two chaingunners waiting in ambush (and an arachnotron on Ultra-Violence and above). Open the brown door at the end of the hall and you will be attacked by two demons and two spectres (not on Hey, not too rough and below). Further up at the T-junction, you will be attacked by an imp and a revenant (demon on Hey, not too rough and below).

At the junction, go right (up the stairs) to find yourself on a ledge in the corner of a slime-filled room with some pillars and ledges. This is a puzzle-like area. Your first order of business is to clear out the monsters on the surrounding ledges - a Hell knight in the southeast, up to three imps in the northwest, three zombiemen on the pillars and two demons on an isolated ledge in the north. Furthermore, there are two spectres (four on Ultra-Violence and above) in the slime, and they can use the teleporters intended for you to get back up to get onto your ledge. Get to work, and while you're on it, blow up all barrels on the ledges you see - you'll be visiting most of these ledges later while under fire from hitscanners. The sequence of events, ending with the collection of the yellow key, is:

  1. Once ready, flip the switch on the south wall of the ledge you are on. This causes rails to rise out of the slime, joining some of the pillars. (While there is a gap between the rails, the gaps are 28 units wide, so you are at no risk of falling in.) Up to four zombiemen will also teleports onto the pillars in the room - use your chaingun to sort them out. Follow the rails to the northern ledge (where the demons were).
  2. As you reach the northern ledge, the first set of rails sinks back into the slime. Flip the switch. A second set of rails will rise out the slime, and this time up to four shotgun guys will teleport onto the pillars.
  3. Follow this second set of rails to the southeast ledge (where the Hell knight was). Open the door in the east and clear out up to three shotgun guys and two chaingunners inside. Flip the switch in the northeast to raise a third set of rails. Up to two shotgun guys and two chaingunners will teleport onto the pillars.
  4. Follow the third set of rails to the ledge in the northeast. Head all the way to the end of this ledge, where an access panel is. Flip it, then backtrack and flip the switch on the east wall to raise the fourth set of rails. Up to four imps will teleport onto the pillars.
  5. Follow the fourth set of rails back to the southeast ledge. A panel to the south is now open, leading to a room with a baron of Hell and a super shotgun. Quickly take it and begin unloading on the baron. Once the monster is dead, flip the switch on the east wall and wait for a short while. The slime in the three pipes in this room will lower, revealing the yellow skull key in the middle one.
  6. Head back out and flip the switch next to the open panel to raise the final set of rails. Follow the rails back to the starting ledge, and this area is complete.

Blue Key

Backtrack to the brown door that you used to enter this area. Just next to it is an alcove with a cylindrical metal structure, with an inverted pentagram on the wall next to it. Head into this alcove and flip the switch on the left to lower the structure, revealing it to be a platform. Ride this platform up and open the door at the top. This takes you to a corridor leading to a series of small "control rooms". As you enter the first one, watch for up to two imps and two shotgun guys. Open the door to the south, and watch for a spectre in the connecting corridor. Open a second door to the south and clear out an imp, zombieman and a chaingunner (not on hey, not too rough and below) in the second control room. Open the final door to the south, and in this L-shaped corridor you will find two Hell knights. Use your super shotgun to kill them before you get boxed in.

At the end of this L-shaped corridor, equip your chaingun and open the door. Mow down the group of up to two zombiemen, two shotgun guys and two chaingunners lying in wait. Use the switch to the right of the raised silver circular platform ahead to lower it, and prepare to do battle with an arachnotron. Ride the platform up and prepare to do battle with a second arachnotron (Ultra-Violence and above only). At this point, you have probably woken up all of the monsters in the outdoor area ahead, but you shouldn't waste time dealing with them. Instead, try to get the pain elemental in this outdoor area out of the picture first (as well as any cacodemons that wander in). The green force field ahead blocks movement, but not projectiles, so use it to your advantage.

Instead of going to the outdoor area, look left of the force field to find a silver door. Open it, equip your chaingun and climb up to the top (watch for any imps that may have opened the door at the top). At the top, open the second silver door to reach the highest L-shaped ledge in the outdoor area. It is full of imps (and one Hell knight at the end). You only have to deal with these monsters and any floating ones from earlier, so this should ease the load on your ammo.

At the end of the ledge, head through the door into an office-like area. In here, there are two zombiemen, a shotgun guy, up to two chaingunners and up two demons to deal with. Head around the desk and flip the switch to open the door in the northeast. Follow the red floor around to a door and head through to a brown hallway with metal structs. Here, you have to deal with three imps and a baron of Hell (two on Ultra-Violence and above). Head to the middle section of the hallway and open the left (north) door.

As you enter, you will be attacked by Hell knights from both sides (right side only on Hey, not too rough and below). Pull them out and deal with them. After you are done, go left at the junction. Head along the corridor and clear out four imps and four zombiemen at a grey "lounge" area. Head to the partially lowered door and look right (east) to find a silver door between "poison" signs". Open the door and drop down to a brick sewer area.

In this sewer area, the slime is damaging, so stick to the dry sides. Your job is to make a big loop clockwise to unlock the chamber with the blue key in the north. In order, these are the threats you will face:

  • Three spectres at the first junction
  • Two cacodemons (one on Hey, not too rough and below) at the northern stretch
  • Up to two shotgun guys, two zombiemen and two chaingunners at the southeast section (watch for the barrels here!)
  • A baron of Hell in the switch chamber

Flip the switch in the baron's chamber to raise the bars clocking access to the blue key chamber in the north. Backtrack to the blue key chamber, kill the Hell knight inside and clear the revenant and shotgun guys in their alcoves. Head around to the back of the walkway and flip the switch to lower the blue key, which you can now collect.

Normal Exit

Backtrack to the partially lowered door, and all the way back to the junction where you were ambushed by Hell knights. On your way back, watch for up to four chaingunners that have teleported into the sewer area. This time, go right at the junction (north). Turn the corner and deal with a mancubus (four imps on Hey, not too rough and below). Head into the door next to where the mancubus was, flip the switch to lower a platform, then puncture the cacodemon inside. Ride the platform up to a door leading to a D-shaped control room overlooking a helipad. Kill the zombieman, three shotgun guys and chaingunner in here, then flip the switch in the north of the room.

Backtrack to where the mancubus was. The door marked "exit" will now be open. head through it. Your final opposition is up to four spectres and two arachnotrons. Flip the switch at the end of the helipad to end the level.

Other points of interest[edit]


  1. In the brown hallway with metal structs, which is in the southern part of the map, use the switch near the south door to open it. Walk onto the computer terminal in this small room using the light on the floor and press the red panel, which allows you to get the plasma gun and energy cells in the room. (sector 1266)
  2. From the door leading to Secret #1, take the other door to another brown-floored hallway and take a left. In the lounge area with the zombiemen inside, press on the red, vent-like panel to lower it into a small corridor with health bonuses. (sector 1262)
  3. Inside of Secret #2, one of the pickups is actually an armor bonus. If you pick it up, look closely at the floor and you will see a small area pointing east. Press on the wall it points to to get the red skull key. (sector 1250)
  4. In the puzzle-like area at the northeast part of the map, the eastern computer room has a red door. Once you get the red key from Secret #3, head back here to open the door to a hellish room containing an arch-vile and a switch. (sector 452)
  5. The switch that is pressed in Secret #4 raises a walkway on the western side of the puzzle room. Make your way there and open the vent shaft to drop in. From where you drop, go right, moving northwest through the shaft until you reach a fork where a lost soul attacks from the left and another fork is to the right. From where the lost soul was, open the shaft to a small room with monsters, medikits, a BFG9000, an energy cell pack, and a switch. (sector 413)
  6. At the fork mentioned in Secret #5, go right, and then right again (there is another lost soul in this fork, but only on Ultra-Violence or higher). The vent should dump into a small room with imps, medikits, and a megaarmor. (sector 365)
  7. Press the switch in Secret #5, then head back to the starting room. Open the door that leads to the yard outside, then open the door in the fleshy depression on your right. (sector 481) If you did not press the switch in Secret #5, you will not be able to open this door.
  8. Inside Secret #7, shoot both of the black marble faces to open the bars that lead to the secret exit, going to MAP31: Mortar Combat. (sector 1197)


Demo files[edit]

Areas / screenshots[edit]


Current records[edit]

The records for the map at the Doom Speed Demo Archive are:

Run Time Player Date File Notes
UV speed (normal exit)
UV speed (secret exit)
NM speed (normal exit)
NM speed (secret exit)
UV max 8:30.14 Dylan Gill (TheV1perK1ller) 2018-03-19
NM 100S
UV -fast
UV -respawn
UV Tyson
UV pacifist (normal exit)
UV pacifist (secret exit)

The data was last verified in its entirety on April 3, 2022.


Player spawns[edit]

This level contains five spawn points:

  1. facing north. (thing 596)
  2. facing south. (thing 597)
  3. facing west. (thing 598)
  4. facing south. (thing 599)
  5. facing east. (thing 600)


Map data[edit]

Things 603
Vertices 7790*
Linedefs 8262
Sidedefs 14131
Sectors 1468
* The vertex count without the effect of node building is 6652.


This level contains the following numbers of things per skill level:

Technical information[edit]

Inspiration and development[edit]


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