Z1M3: Toxin Refinery (Knee-Deep in ZDoom)

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Knee-Deep in ZDoom maps
This level occupies the map slot Z1M3. For other maps with a non-standard slot, see Category:Non-standard map slots.

Z1M3: Toxin Refinery is the third level of Knee-Deep in ZDoom. It is a reimagining of Doom's E1M3: Toxin Refinery with new areas and enemies. The primary designers were Björn Ostmann (Vader) and Pawel Zarczynski (NMN). The par time defined in MAPINFO is 17:00.

The secret exit to Z1M9: Military Base is accessible from this level.

Toxin Refinery was featured in Doomworld's Top 100 Most Memorable Maps, placing 32nd.


Map of Toxin Refinery
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.


Blue keycard[edit]

Collect the shotgun in front of you (on I'm Too Young To Die and Hey Not Too Rough skill levels) then open the door and turn left, following the path past zombiemen (plus shotgun guys and a spectre on higher skill levels) to a silver door. Open the door and blow up the barrel behind it to kill some waiting monsters then head north up some steps and turn left at the top, going down a staircase and turning left to find a button that will open a nearby wall. Go back to the barrel area and head north-west through the wall you just opened, pushing past some shotgun guys to a rectangular computer area. Head round the structure in front of you to its north-west side to find a door, then open this to locate the yellow keycard.

Go back to the barrel area and head north up the steps again, then continue north to a silver door and open it to enter a gray room with zombies and imps. Go through the room and head round the corner to a circular room with two rotating shafts then proceed east to a passage with soul harvesters, which leads to a bridge over three deep nukage pools. Cross the bridge and head round the computer block on the other side to find a yellow key door, open it and go round the corner to find the blue keycard being guarded by a single shotgun guy. When you try to leave the room after collecting the key, the door will slam shut and the lights will turn red; wait for the north and south doors to open and reveal satyrs and kill all of them to re-open the entrance door, which will have a Hell warrior waiting behind it.


Backtrack to the starting area; after passing through the silver door leading to the starting area, head east through two narrow doorways to another silver door requiring the blue key. Open the door and kill the rapid fire trooper blocking your path, then enter the next room and go through the east door. Climb the stairs and follow the passage until you step over a nukage stream, then turn right to see a staircase with one or two soul harvesters on it. Climb the stairs and kill the waiting zombies, then head up another set of stairs and open the door at the top to find some troopers in front of a green door that will not open. Look east to see a lift with a barrel and ride this down to a room with imps and more barrels, then go outside and follow the path round a corner to some zombies. Open the door ahead, watching out for a chainsaw zombie hiding on your right, then kill the chaingunners/troopers in the next room and press the button on the east wall. Kill the blood demons that are released to re-open the entrance door, then return to the lift and ride it back up to find that the green door has opened, letting you collect the orange keycard.

Backtrack to the starting area; after passing through the blue key door, go through the doorway on your right then turn left to see a switch - flip it to lower the lift and go down to the mines. Kill the chainsaw zombies waiting at the bottom of the lift then open the west door to find some demons in a room filled with barrels. Go through the south door to a cross-shaped walkway and flip the switch on the east wall to open a nearby set of bars, then head west over a second crossroads and into a passage with lights. Follow the passage to a third crossroads and head west to another passage, which leads to a room with one or more mauler demons as well as a button that activates the secondary pump. Press the button then return to the second crossroads and wait for the south door to open.

Once the door opens, go through it then press the button in the north-east corner being guarded by a satyr - this will unlock a door elsewhere in the mine which you will need later. Leave the room using the east door and dispose of any waiting monsters, then head south into a tunnel and follow it until you go round a corner to a larger cavern with troopers and an imp; note the door in the north wall as you will need to use it later. Head west into the next cavern with a circular pool of brown water and kill the waiting demons and soul harvesters, then step on the south lift with a chaingun to go down to a chamber with one or two mauler demons. There are two buttons in this chamber protected by chaingunners - press the west button (requiring the orange key) to open the bars blocking the east button, which has a megaarmor in front of it. After pressing both buttons, ride the lift back up and go east into the previous cavern, then open the north door you saw earlier to enter a small room with one or two troopers. Go down the ramp behind the troopers and kill one to three chaingunners who are protecting the red keycard.

With the red key, go back up the ramp and leave the room using the south door then head west to return to the cavern with the circular pool. Go through the east door and follow the passage to a room with shadows guarding a backpack and other supplies, then open the north door (which you unlocked earlier) to confront a stone imp. Go through the door and turn left to find a room with a shotgun as well as a door requiring the red key; open this door to reveal a button that will raise two switches behind you. After flipping both switches, press the button between them to power the generator.


Return to the lift you used to enter the mines and kill two Hell warriors that have appeared here, flip the switch by the lift to return to the starting area then go through the blue key door again. Head north-east through either of the doorways by the nukage pool then follow the passage to a large room with a staircase. Kill any lingering zombies then head up the stairs and open the door at the top. Kill one or more waiting demons then enter the shuttle and press the button inside it - the level will end after a short delay, taking you to Z1M4: Command Control.

Secret exit[edit]

To find the secret exit you will need all six keys - four are acquired by playing through the level, while the green key is found in secret #3 and the silver key is found in secret #7. With all the keys, enter secret #11 and press the button here then go to the neighboring storage area to find that the north door has opened. Kill the satyrs behind the door then open a second door behind them to find a shuttle - its door will slam shut as you approach and a pentagram will appear on the floor. Kill two Hell warriors that teleport in then enter the shuttle and press the switch inside it to move on to Z1M9: Military Base.

Other points of interest[edit]

From the starting area, head north to find a room containing several zombies (this room led to the secret exit in the original level). Look behind the round column in this room to find an armor.

Pass through the blue key door to enter a room with a nukage pool. If you drop into this nukage you can swim into a tunnel, then travel east and south to find a chainsaw.


  1. In the yellow key area, go up the ramp to find three computer terminals with screens. Interact with the two terminals on the north wall to deactivate the red/blue security locks, then use the terminal on the west wall to open an emergency hatch on the computer panel to the south-west. Next to this panel is a second panel with a tiny crate in front of it; press use on the crate to pick it up, then approach the hatch to put the crate down in front of it. You can now jump up to the hatch to trigger the secret. (sector 1496) Go through the east door to find a lift leading to a supercharge.
  2. From secret #1, head into the neighboring room to the south to find one or two spectres guarding a chaingun and backpack. Flip the switch in the south-east corner of this room to display a message saying "Access to disposal area granted.", then return to the yellow key area and pass through the now-open panel in the north-east corner. The chamber behind it contains a berserk pack, a clip, two armor bonuses, a health bonus and a medikit. (linedef 171 via thing 54, ZDoom's "secret trigger" actor)
  3. From secret #2, enter the east tunnel to find a radiation shielding suit then return to the previous room and drop into the nukage by the south wall to find a partially-submerged tunnel. Head north at the first intersection, then west, then north twice to find a 90-degree turn to the left - this leads to a one-way tunnel that ends at a broken door. Blow up the barrels in the south-west corner to open a hole in the wall and go through it to find a megaarmor in front of a dead Duke Nukem in a barrel. (sector 3545) The green keycard can be found next to Duke, and a shotgun can be found by a dead pig cop elsewhere in the room.
  4. In the corridor leading to the blue key with a ladder in the south-east corner, interact with the computer terminal on the west wall that has a red screen. This will reveal a backpack to your right. (sector 1894)
  5. Climb the ladder mentioned in secret #3 to find a shotgun, a box of shotgun shells and other items guarded by shadows. (sector 1858) Head south-east to find a button that will open the next secret.
  6. After pressing the button near secret #4, go to the outdoor area with nukage just before the blue key room then drop into the north pool and swim to the bottom. Head north into a tunnel leading to a rocket launcher and two rockets; taking the rocket launcher triggers the secret. (thing 479 via thing 478, ZDoom's "secret trigger" actor)
  7. In the orange key room, look south-east through the windows to see a terrorsphere on top of a hill. Climb the hill by running and jumping, then collect the terrorsphere to trigger the secret. (thing 809 via thing 2128, ZDoom's "secret trigger" actor)
  8. On the west side of the mine is a bridge over a brown water pool. Drop into the water and swim under the bridge to find a tiny button on the north wall, press it then quickly swim south-east to an open grate. If you can enter the grate before it closes, you will find a silver keycard. (sector 5651)
  9. From the bridge over the brown water in the mines, head north into another cavern. Enter the passage in the north-west corner to find a chaingun and a backpack. (sector 5965)
  10. From secret #9, head east and north to a storage area. With some care, you can jump up the boxes on the west side of this area to reach a window where soul harvesters are guarding a berserk pack, two health bonuses, a box of shotgun shells and a box of rockets. (sector 5109)
  11. From the storage area where secret #10 is found, head south-east to a lab with two translucent tanks. Between the tanks are two sloped panels - press use on the south panel, then head west through the storage area to a second pair of tanks to see that a button has been revealed in the west wall. Pressing the button will open a secret room behind you containing a blood demon as well as a backpack, an armor, a medikit and some armor and health bonuses. (sector 6627) There is another button in this room - if you have all six keys, you can press this button to open the way to the secret exit.

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 12:23 Andrew Usher 2016-05-22 kdizd_usher.zip
NM speed
UV max 21:00 Andrew Usher 2016-05-22 kdizd_usher.zip
NM 100S
UV -fast
UV -respawn
UV Tyson
UV pacifist

The data was last verified in its entirety on December 12, 2021.


Map data[edit]

Things 2190
Vertices 25681
Linedefs 34400
Sidedefs 60100
Sectors 8112


This level initially contains the following number of things per skill level. It does not include things spawned via scripts.

Monsters 1-2 3 4-5
Zombieman 17 23 15
Rapid fire trooper 15 26 34
Shotgun guy 11 24 49
Chaingunner 6 7 15
Chainsaw zombie 2 5 8
Rocket guy 0 1
Imp 25 33 47
Stone imp 6 9 12
Dark imp 0 1
Shadow 17 26 30
Soul harvester 13 29 45
Demon 8 12 19
Spectre 3 7
Mauler demon 8 13 17
Blood demon 5 7 10
Satyr 6 10 15
Weapons 1-2 3 4-5
Chainsaw 1
Shotgun 4
Chaingun 3
Rocket launcher 1
Ammunition 1-2 3 4-5
Clip 34
Box of bullets 8
4 shotgun shells 39 42
Box of shotgun shells 12
Rocket 6 7
Box of rockets 1
Health & Armor 1-2 3 4-5
Stimpack 26 27 31
Medikit 25 26
Armor 5 4
Megaarmor 2
Items 1-2 3 4-5
Armor bonus 56 57 63
Health bonus 76 80
Supercharge 1
Terrorsphere 1
Backpack 7
Berserk 2
Radiation shielding suit 4 5
Keys 1-2 3 4-5
Blue keycard 1
Red keycard 1
Yellow keycard 1
Orange keycard 1
Green keycard 1
Silver keycard 1

Level designers[edit]

Primary mapping[edit]

Secondary mapping[edit]

Tertiary mapping[edit]

External links[edit]