Doom Wiki
This article is a stub. Please help the Doom Wiki by expanding it.

DELTA COMPLEX - "The Delta Complex is the most advanced research facility on Mars. The complex is divided into three main sectors each serving unique purposes and one smaller sector that houses the main test portal. Access can only be gained through the Monorail or CPU Complex."

Delta Complex: Union Aerospace Research Division (also called Delta Labs Sector 5 in the autosave) is the twenty-first level of Doom 3. It is mostly a revisit (though there are a few previously unexplored areas) of various sections of the previous Delta Labs levels (Level 1, 3, and 4). The main portal has been sealed, but the player will learn from Betruger that there is another Hell Hole on Mars still active, making the invasion ongoing. The player will then find a wounded Swann, explaining that Sergeant Kelly has now sided with the demons before revealing the Hell Hole's location in the Caverns.

Once more, the player loses their weapons on the journey back from Hell (with the exception of the Soul Cube) and must collect them all again. From here on, enemies will appear in much larger numbers, forcing the player to test out their Soul Cube for the first time. With the exception of Commandos, the Zombie classes no longer appear at this point in the game. Ticks make their first and only appearance.


  • Teleporter 4 Main Chamber
  • Sub-Floor
  • Service Duct
  • Teleporter 4 Entrance Hall
  • Teleporter 4 Entrance Hall 002
  • Level 3 Airlock
  • Teleporter 4 Access
  • Hydrogen Storage Transfer
  • Level 1 Elevator Access
  • Elevator Shaft
  • Elevator Vent Duct
  • Delta Service Tunnel 1
  • Delta Service Tunnel Airlock
  • Lift Access and Storage
  • Delta Authority Systems
  • Delta Service Elevator
  • Delta Authority Junction
  • Delta Authority Lobby
  • Delta Authority Hallway 1
  • Delta Main Lobby
  • CPU Access
  • Transfer Bay


You begin in the Hell Knights duo room, with only the Soul Cube in hand. Grab the Pistol and Machine Gun in the boxes near the closed door, then jump into the hole on the floor, picking up the Flashlight, Grenades, and some ammo in the process. At the end, you'll have to fight a Chaingun Commando. Pick up his Chaingun, then take the rear door (the one which doesn't look like a sas). Kill the Tentacle Commando who lurks here, then pick up the Chainsaw. You can now enter the sas-looking door. As usual, you won't be able to go back.

You are in the final area of Delta Labs Sector 3; the room with the damaged bridge. Run toward the starting area and turn left to place yourself in the Delta Labs Sector 3's final teleporter landing pad. It is a safe place to deal with the long swarm of ticks coming up. Just sit here and make one of the longest usage of the Chainsaw of the game, out of the tick's reach. Once they are all dead, proceed to the other corridor; the one which led to an inactive locked door in the Delta Labs Sector 3 level. It's now blown open. As you walk in the now tick-ridden corridor, a Tentacle Commandos will teleport in front of you. Walk a bit further and a second one will teleport right behind you. It's suggested to keep the Soul Cube in your inventory and simply kill them with the Chainsaw. There is a Plasma Gun, 5 Grenades, and some ammo on a shelf right before the door. Then go in the elevator shaft, climb the ladder inside it, and crawl through the vent. You'll now be above a tunnel of a previous level, precisely the second garage-like corridor of Delta Labs Sector 1, the one after the large generator room. From here, you'll revisit a portion of this level. You'll see a Chaingun Commando patrolling nearby. Once again, if you jump in, you can't backtrack. It's best to jump without killing any enemies for now.

Now that you are on the same platform as the Commando, unleash the Soul Cube on him. Be careful as the cube won't always target this enemy. After killing the patrolling Chaingun Commando, wait a bit; a Tentacle Commando will run at you from behind a crate. Walk a bit more and the wall in front of you will open, revealing an Arch-vile, and spawning another Tentacle Commando from where you landed. Once the place is pacified, search around the crates to recover a Shotgun and an Adrenaline boost. Follow the path, a second Arch-vile will come from the exit door, and a Tentacle Commando will run at you from the point where you landed. Behind the door is a small lift room. Call for the lift and go on the floor level. Once on the lower floor, walk a few steps and kill the Chaingun Commando coming from the front door. The next room has a flight of stairs, with a Revenant behind the door at the top. The door leads to a small room with an empty Health Station (perhaps it's related with how many you took and left during the first visit, in Delta Labs Sector 1) and an elevator for Delta Labs Authority. Take the elevator and, when you exit it, you are in a circular room, with only one open door. Indeed, the now opened door was closed in the first visit, and the now closed one is open for the second visit. The door leads to the desk room. It has been previously visited, but this time a badly wounded Swann lies here. Listen to him, grab his PDA, and continue. The next corridor is overtaken by demonic growth, and there is a hole in the floor. Crawl in, get the ammo, armor, and health there is on a shelf, and at the end, activate the maintenance ladder, which will open a trap on the floor.

The ladder leads to the "map room" of Delta Labs Sector 1, although heavily modified and reduced, due to demonic growth taking over the facility. As you arrive, the ladder retreats and an Arch-vile teleports near you, followed by a Tentacle Commando. Kill them quickly as a second Arch-vile and Tentacle Commando duo appears rapidly. Once the place is pacified, collect the Medkit on a chair and the PDA near the map screens. It will allow you to reclaim a Rocket Launcher at the beginning of the next level. Swann's PDA allows to open the larger CPU Complex door. There is a final Revenant to kill here, unless you return to the map room, which trigger an Arch-vile to appear before you. There is a hidden Ammo Belt in the last room, as well as a monitor from which you can download information about demonic rites, right next the exit door.


Email Downloads (Personal Email Inbox)[]

  • Research Archive / Valuable Sacrificial Pointers




Cabinet Codes[]