Underground (Part 2)

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The Lost Mission maps
Underground 2 Title Screen.jpg

Underground - Sector 2: Mars City Service Sub-Level is the fourth level of The Lost Mission. In this level, the marine must be led by a sentry bot to the elevator that leads to Exis Labs, and on the way, the marine must fight a bunch of heavy-weight foes. The player can obtain rocket launcher in this level, as well as a chaingun, if they haven't done so in the last level. Cacodemons, revenants, chaingun commandos and Hell knights first appear here.


Spoiler Warning: Plot details follow.

As usual, the marine proceeds through various corridors and kills everything on his way. Early on, he encounters a sentry bot station and activates it. Then he continues to proceed through various corridors and kill everything, but this time with a sentry bot. After a while he enters Main Service Lift room and gets attacked by Hell knights which also likely destroy the sentry bot. After killing them, he goes to Transfer Control and finds there a power cell to power up the lift, then he takes the lift. It takes him to Exis labs.

Spoilers end here.


Find Service Access to Exis Labs
Traverse service sub-levels to reach Exis Labs.
Restore Power to Service Lift
Acquire power cell from Transfer Control area.
Use power cell to restore power to main service lift.
Take Service Lift to Exis Labs
Use main service lift to reach Exis Labs.





The monster count is the same on all skill levels.

Enemies Amount
Zombie 7
Machine gun Z-Sec 5
Shotgun Z-Sec 2
Imp* 16
Cacodemon 4
Revenant 7
Tentacle commando 4
Chaingun commando 2
Arch-vile 2
Hell knight 2

* Two of the imps are crawlers. Some of the imps are spawned by the arch-viles, so their amount may vary. Here only a number of distinct spawn points is shown.


The item count is the same on all skill levels.

Items Amount
Shotgun 3
Machine gun 2
Chaingun 1
Rocket launcher 1
Shells (small) 5
Clip (small) 3
Clip (large) 3
Grenades 3
Ammo belt 7
Rockets (small) 1
Rockets (large) 1
Med kit (small) 7
Med kit (large) 5
Armor shard 22
Security armor 3
Power cell 1

There are two health stations with 100 health each on the level.

Locker codes[edit]

For the sources of the codes, see Doom 3 locker codes.
  • Storage locker #108 - Ammunition: 847. Contains: med kit (large), security armor, ammo belt, rockets (large).


  • In Sub-Level Corridor SL-1A one can jump over the railing to get a security armor.
  • In Sub-Level Security one can also jump over the railing and find supplies under the floor, then crawl along the pipes and climb up the ladder to find a hidden room with a chain gun.
  • Upon entering the Main Service Lift area, turn to the right and a small dark compartment with supplies can be found.


  • Unlike the sentry bots found in Doom 3 and Resurrection of Evil, this level has an infinite supply of sentry bots. If your companion is destroyed, you can simply return to the sentry bot station and activate another.