Mars City: Union Aerospace Corporate Division


Doom 3 maps
Map name: game/mars_city2
"Marine? I can't believe you're still alive."
― Sergeant Kelly [source]

Mars City: Union Aerospace Corporate Division is the third level of Doom 3. The same level as Mars City, but after the demon invasion. The marine is given his mission to link up with Bravo Team in this level. This is where the demo ends.


Mars City Title Screen.png
Spoiler Warning: Plot details follow.

The Player returns to Mars City to find the place in chaos. The sounds of battle can be heard coming from the walls, but at this point, most of Mars City has already fallen.

Fairly early in the level, the Player encounters a survivor Roland who is hiding in the ventilation shaft near the elevator. Roland extends a ladder, allowing the Player to climb into the shaft. He then urges the Player to go get help.

The Player uses the ventilation shaft to enter the Manifest Control Office, and from there, fights his way through Security Operations to the Infirmary. From there, he gains access to Marine Command and arrives back at Marine HQ. All the marines stationed there are dead, but a communications console is still working and has an incoming transmission from Sergeant Kelly, who is pleasantly surprised to see you're still alive.

Sergeant Kelly informs the Player that he is trapped in the Delta Complex and has decided to set up a command post there. He orders the Player to link up with Bravo Team and help them send a distress call to the Earth Fleet. In order to reach Bravo Team, the Player must head through Alpha Labs. Kelly also updates the Player's security clearance, giving him access to the ACO section of Mars City.

With the aid of a surviving Sentry Bot, the Player fights his way through the ACO area to the elevator. From there, he rides the elevator to the next level: Administration.

Spoilers end here.



Note: Includes only enemies that can be fought and killed.

Enemy Recruit Marine Veteran
Zombies 9 10 10
Flashlight zombies 1 1 1
Fat zombies 1 1 1
Fat wrench zombies 1 1 1
Flaming zombies 2 2 2
Morgue zombie* 1 1 1
Pistol Z-Secs 8 8 8
Shotgun Z-Secs 1 3 4
Machine gun Z-Secs 15 18 19
Imps 4 5 7

* The only one in the game.


Item Recruit Marine Veteran
Shotguns 2 2 2
Machine guns 4 4 4
Bullets (small) 2 2 2
Shells (small) 8 8 8
Shells (large) 1 0 0
Clips (small) 6 6 6
Clips (large) 10 7 6
Med kits (small) 6 5 5
Med kits (large) 15 13 9
Armor shards 40 37 33
Security armor 8 6 5
Adrenaline 1 1 1
ACO keycard 1 1 1

There's also one health station on the level, with 100 health in reserve.


  • Marcus Stanton: Found in Manifest Control Office
  • Marcus Caseon: Found in Infirmary.
  • Bill Tyson: Found in Marine Command, in corridor behind flaming pipe.
  • Duncan Mathews: Found in ACO Lift Junction. Requires going through a service access on the right of the room.

Cabinets/Door Codes[edit]

  • Cabinet #017: 347. Learned from Marcus Caseon's second audio log. Contains: med kit (large), security armor, clip (small), shells (small) x2.
  • Mars City Armory: 584. Learned from Bill Tyson's PDA. Contains: shotgun x2, machine gun x2, clip (large) x2, shells (small), med kit (large), security armor (2 on Recruit, 1 on Marine/Veteran).


  • When you encounter the sentry bot, you can go back to reception where you were a PDA at the start of the game. There, you can access a nearby room with supplies by jumping through the window with missing glass panel.


  • In Infirmary where you get attacked by the unique morgue zombie, if you kill said zombie before it manages to get up from its bed, the one or two (depends on the skill level) machine gun Z-Secs won't spawn. This is likely a bug, as it seems the trigger for the Z-Sec(s) to appear is scripted to work after the morgue zombie's get up sequence is finished.
  • If you go into the bathroom and look at yourself in the mirror, you will see a vision of yourself turning into a zombie. When the vision ends, an Imp will spawn outside.
  • In the Demo version, when you complete the level, your vision will turn red and evil laughter will be heard.


External links[edit]

  • Walkthrough video by WoopzillaWalkthrough (part 1; part 2) on YouTube. Veteran difficulty; part of a full game run.