Difference between revisions of "Mars City Underground: Union Aerospace Subsystems"

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Revision as of 13:38, 18 April 2020

Doom 3 maps

Mars City: Intro 1 2 3 Alpha Labs: 1 2 3 4 Enpro Communications: 1 2 Monorail/Recycling: 1 2 3 Delta Labs: 1 2a 2b 3 4 Hell Delta Complex Central Processing: 1 2 Excavation: 1 2 3 End
Map name: game/mc_underground

"All units. This is Sergeant Kelly. We're under attack by an unknown enemy force. Fall back to Marine HQ to regroup! I say again fall back to Marine HQ and await further orders!"

― Sergeant Kelly ^[source]

Mars City Underground: Union Aerospace Subsystems is the second level of Doom 3, composed of the main area and an abandoned communications building separated by a short walk outside. It is a small tutorial level covering a few more features in the game.

In the Communications Building, things start to go awry, and the action begins here. The player receives the first weapons: flashlight, pistol, shotgun, and an optional machine gun, and is introduced to the first enemies: zombies, Z-Secs, and the imp, the first hellspawn enemy, is introduced in a cutscene.

Summary

Map overview.

A detailed walkthrough is available for this level.

Spoiler Warning: Plot details follow.

The marine arrives at the Mars City Underground, where he is greeted by T. Brooks, who gives him access to some basic gear: armor, a flashlight, and a pistol. The marine then heads through the facility to the old comm station where the missing scientist is believed to have gone. Along the way, he runs into several workers, all of whom seem to be nervous and on the edge. After a brief walk across the Martian surface, he reaches the old comm station. Inside, he finds the missing scientist - Jonathan Ishii - trying to send a message to the UAC.

Ishii frantically tries to explain that he must send a warning out while there is still time. Before he can explain further, another teleportation experiment is conducted at the Delta Complex. Something goes horribly wrong, however. The portal stabilizers suddenly fail, causing a series of explosions throughout the base. At the same time, mysterious ghost-like skulls come flying out of the portal, possessing many workers and security guards. Ishii is possessed and transformed into a zombie, which attacks the marine. After killing the zombified Ishii, along with a Z-Sec that bursts in moments later, the marine receives orders over the radio from Sergeant Kelly to fallback to Marine Command to regroup.

The marine must backtrack his way to the elevator at the beginning of the level. At one point, he is forced to take a detour through Engineering, and must use Frank Delahue's PDA to access the area. Along the way, he is attacked by zombies and Z-Secs, and eventually imps. Throughout all this, the screams and panicked shouting of fellow marines can be heard over the radio. Sergeant Kelly is heard trying to coordinate a defense, but it is obvious that the battle is going poorly. Eventually, the marine returns to the elevator and rides it back to Mars City.

Objectives

Reach Old Comm Building: Make your way to the old communications building. The missing scientist was last seen heading that way.
Back to security checkpoint: Make your way back to the Security Checkpoint. From there you can take the elevator back up to Mars City.

Spoilers end here.

PDAs

Daniel Young. Obtained by killing Daniel Young.
Mark Ryan. Obtained by killing Mark Ryan.
Grant Baston. Found in Energy Stabilization Unit, near a storage crate.
Frank Delahue. Found in Energy Processing, on a table.

Characters

Statistics

Enemies

Note: Includes only enemies that can be fought and killed. The enemy count on Nightmare is the same as on Veteran. There are no changes in the enemy amount in the BFG Edition.

Enemy	Recruit	Marine	Veteran
Zombie*	18		19
Pistol Z-Sec	4
Shotgun Z-Sec	4		5
Imp	11

* The zombie that attacks a scientist in Energy Processing has only 20 health.

Items

The item count on Nightmare is the same as on Veteran, except the med kits are absent. There are no changes in the amount of items in the BFG Edition.

Item	Recruit	Marine	Veteran
Flashlight	1
Pistol	2
Shotgun	4
Machine gun	2
Bullets (small)	15	13
Shells (small)	14
Shells (large)	2	1
Clip (small)	2
Clip (large)	1
Cells (small)	2
Med kit (small)	23	18	15
Med kit (large)	2
Armor shard	83	76	73
Security armor	3
Adrenaline	1
Air canister	3

There are also 4 health stations on the level: two of them have 100 health in reserve, one has 50, and another has 80 (in BFG Edition all health stations have 100 health).

Locker codes

For the sources of the codes, see Doom 3 locker codes.

Storage locker #023 - Supplies: 531. Contains: med kit (small), shells (small), armor shard x3.

Secrets

In Underground Security (the first room), there are two armor shards on a hidden ledge in the corner to the left of the entrance where the pipes are (one needs to climb those pipes to reach them).
In Underground Junction (the crane area), one can climb into crane cabin and find shells and two armor shards there. To reach the platform from which the crane can be accessed, the player needs to go downstairs in underground junction and find a cable that leads to that platform, which is located behind one of the pillars (there's a hidden med kit there). Once the platform is reached, the crane has to be turned to the load position by clicking on a nearby control panel. Note that after the invasion the crane becomes inaccessible because the control panel is broken. In the same platform there is a door to the maintenance storage. It's locked before the invasion, but can be opened after, from the security checkpoint (see below). There's another armor shard there, on the top of two boxes.
In Maintenance Area CS1, there are two armor shards hidden behind the stairs, and more on top of the machine that C. Rodgers repairs (can be access by jumping on crates then on pipes). These items are inaccessible after the invasion, due to the whole room being wrecked.
In Energy Processing, there are some armor shards below the floor plates.
In Energy Delivery, the player can climb below the bridge using a ladder nearby, and access bullets, a med kit and armor shards.
In Maintenance Area PD1, there are shells and armor shards below the stairs that can be reached by carefully jumping onto the adjacent pipe.
In Mars Surface there are an armor shard, an adrenaline and a air canister lying behind the airlock the player first comes from. Also here, one can climb onto the hill to the left of the opposite airlock to access a clip, armor shards and one more air canister.
In Old Comm Storage, some armor shards and a med kit can be found on the shelves to the right of the airlock.
In Old Comm Main, some bullets (and a med kit on Recruit) can be found on the tables (hard to see because of darkness).
In the room with Frank Delahue's PDA (Energy Processing), there are bullets, shards, and a med kit on a ledge near the table, and two more shards on a tall blocky machine nearby (both can be reached by stacking crates that are lying nearby). In the same room, the player can walk on a pipe to find another ledge with a med kit and shards.
In EP Aerobic Stabilizer, there's a large pipe that can be climbed under, and behind it a med kit and two armor shards can be found.
In EP Control Unit, shells and a med kit can be found under the floor (a ladder can be used to climb back up).
In the room where the player first encounters an imp (also called EP Aerobic Stabilizer), there are a med kit, shells and armor shards on the table behind the stream of fire emitting from the gas pipe. To access it without taking damage from the fire, the player needs to input a failure code into the first control panel in the next room the player has go through, to shut down the gas leak. The code is 842, and it can be obtained by listening to one of the audio logs from Frank Delahue's PDA.
In the same room where the player can shut down the gas leak, the player can also use the third control panel to open a maintenance hatch nearby for some shells and another med kit
After the player passes through the catwalk above the folding bridge and enters the next room (Energy Processing), there are hidden bullets to the immediate right, on a blocky machine.
In Energy Stabilization Unit the player is attacked by a shotgun Z-sec upon entering it. After that, if the player goes a few rooms back, they will find a closet from which the Z-sec emerged and some shells and armor shards in it.
In Underground Security where the player needs to use a control panel to open access to the exit elevator, the same control panel has additional access options which can be revealed by pressing the "Mars City Sublevel Access" button below. There the player can open the exit locker which contains the first machine guns, shotguns and clips, as well as unlock the door to maintenance storage. To access the maintenance storage the player has to go to the isolated platform with the crane (see above). The maintenance storage has a health station, bullets, early cells for the plasma gun, and armor shards (on the crates).

Trivia

On the Nightmare difficulty, you can kill the civilians to get an early charge for the Soul Cube.
At one point, the player will find a scientist being attacked by a zombie on a floor above them. If the player saves the scientist by shooting the zombie, later on they will find an opened (but broken) storage cabinet with health and armor in it. If the player doesn't save the scientist, the same cabinet will be closed with no way of opening it.

Gallery

Underground Security (starting area).
Underground Junction.
Mars Surface.
Old Comm Building.
Beginning of the Hell invasion.
Imp breaks a door.
Energy Delivery.
Energy Processing.
EP Control Unit.
Imp introduction.
Energy Processing, plasma collector room.

External links

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

@@ Line 1: / Line 1: @@
-{{level stub}}
+{{Doom 3 maps|pic=Mars City Underground Titlepic.png|map=game/mc_underground}}
-{{Doom 3 maps}}
 {{Quote|All units. This is Sergeant Kelly. We're under attack by an unknown enemy force. Fall back to Marine HQ to regroup! I say again fall back to Marine HQ and await further orders!|Sergeant Kelly|Doom 3}}
@@ Line 6: / Line 5: @@
 '''Mars City Underground: Union Aerospace Subsystems''' is the second level of [[Doom 3]], composed of the main area and an abandoned communications building separated by a short walk outside. It is a small tutorial level covering a few more features in the game.
-In the Communications Building, things start to go awry. The action begins here, and [[Zombie (Doom 3)|zombies]] are first seen. The [[Imp (Doom 3)|Imp]] is introduced in a cutscene.
+In the Communications Building, things start to go awry, and the action begins here. The player receives the first weapons: [[Flashlight|flashlight]], [[Pistol (Doom 3)|pistol]], [[Shotgun (Doom 3)|shotgun]], and an optional [[Machine gun|machine gun]], and is introduced to the first enemies: [[Zombie (Doom 3)|zombies]], [[Z-Sec]]s, and the [[Imp (Doom 3)|imp]], the first hellspawn enemy, is introduced in a cutscene.
 ==Summary==
+[[File:Mars City Underground Level Scheme.png|thumb|right|Map overview.]]
+{{walkthrough}}
 {{spoiler}}
-The Player arrives at the Mars City Underground, where he's greeted by T. Brooks, who gives him access to some basic gear: armor, a flashlight, and a pistol.  The Player then heads through the facility to the old comm station where the missing scientist is believed to have gone. Along the way, he runs into several workers, all of whom seem to be nervous and on the edge. He also picks up [[Grant Baston]]'s PDA, which contains a code for a locker containing supplies. After a brief walk across the Martian surface, he reaches the old comm station. Inside, he finds the missing scientist - [[Jonathan Ishii]] - trying to send a message to the UAC.
+The marine arrives at the Mars City Underground, where he is greeted by T. Brooks, who gives him access to some basic gear: armor, a [[flashlight]], and a [[Pistol (Doom 3)|pistol]].  The marine then heads through the facility to the old comm station where the missing scientist is believed to have gone. Along the way, he runs into several workers, all of whom seem to be nervous and on the edge. After a brief walk across the [[Mars|Martian]] surface, he reaches the old comm station. Inside, he finds the missing scientist - [[Jonathan Ishii]] - trying to send a message to the [[UAC]].
-Ishii frantically tries to explain that he must send a warning out while there is still time. Before he can explain further, another teleportation experiment is conducted at the Delta Complex. Something goes horribly wrong, however. The portal stabilizers suddenly fail, causing a series of explosions throughout the base. At the same time, mysterious ghost-like skulls come flying out of the portal, possessing many workers and security guards. Ishii is possessed and transformed into a zombie, which attacks the player.  After killing the zombified Ishii, along with a Z-Sec that bursts in moments later, the Player receives orders over the radio from Sergeant Kelly to fallback to Marine Command to regroup.
+Ishii frantically tries to explain that he must send a warning out while there is still time. Before he can explain further, another [[teleporter|teleportation]] experiment is conducted at the [[Delta Complex]]. Something goes horribly wrong, however. The portal stabilizers suddenly fail, causing a series of explosions throughout the base. At the same time, mysterious ghost-like skulls come flying out of the portal, possessing many workers and security guards. Ishii is possessed and transformed into a zombie, which attacks the marine. After killing the zombified Ishii, along with a [[Z-Sec]] that bursts in moments later, the marine receives orders over the radio from [[Sergeant Kelly]] to fallback to Marine Command to regroup.
-The Player must backtrack his way to the elevator at the beginning of the level. At one point, he is forced to take a detour through Engineering, and must use [[Frank Delahue]]'s PDA to access the area.  Along the way, he is attacked by zombies and Z-Secs, and eventually Imps. Fortunately, the Player also picks up a couple of better weapons - the shotgun and the machine gun. Throughout all this, the screams and panicked shouting of fellow marines can be heard over the radio. Sergeant Kelly is heard trying to coordinate a defense, but it's obvious the battle is going badly.
+The marine must backtrack his way to the elevator at the beginning of the level. At one point, he is forced to take a detour through Engineering, and must use [[Frank Delahue]]'s PDA to access the area. Along the way, he is attacked by zombies and Z-Secs, and eventually imps. Throughout all this, the screams and panicked shouting of fellow marines can be heard over the radio. Sergeant Kelly is heard trying to coordinate a defense, but it is obvious that the battle is going poorly. Eventually, the marine returns to the elevator and rides it back to Mars City.
-Eventually, the Player returns to the elevator and rides it back to Mars City.
+===Objectives===
+; Reach Old Comm Building
+: Make your way to the old communications building. The missing scientist was last seen heading that way.
+; Back to security checkpoint
+: Make your way back to the Security Checkpoint. From there you can take the elevator back up to Mars City.
 {{endspoiler}}
-==Walkthrough==
-The trip to Jonathan Ishii is a simple follow the corridor sequence.
-When you meet him, hell breaks loose, with Johnathan being transfored to a zombie within a few seconds.  Kill him quickly, and turn your attention to the door on the left, watching for the Z-Sec that exits and attacks.  Head to the elevator, and go to the first floor.  Exit the airlock, and renter the airlock in the other building.
-When you return to the first building, there is a zombie to the right on the first floor.  Ascend the stairs, and open the door to engage the zombie that attacks at point-blank.  Head up the stairs and into the room with the bridge.  Kill the zombie there, and extend the service bridge to cross it. There is a Z-Sec that attacks from an alcove just past the bridge. Enter the door.
-A Z-sec will take cover behind a crate, and a zombie will approach froma  crawlway in the left.  Search this room for the Frank Delahue PDA to unlock the door and enter.
-A scientist calls for help from the platform above, and you can kill the zombie as it approaches.  There is also a second zombie around the corner to the right. Go through the door on the left.
-Watch the floor, it's exposed machinery.  If you want armor and a shotgun, there is some to the right, but it activates an ambush where the floor lowers and zombies attack from the sides.  Climb the ladder to return.  Exit through the door on the left corner of the room.
-Head down the corridor, and engage the Z-Sec and two zombies at the top of the stairs.  Walk backwards past the stairs to engage the flanking zombie that attacks from a closet, and turn forwards to get the non-flanking zombie. There's a health station at the end of this corridor, which you can use to heal.
-Past the door is a cutscene with a new enemy.  Two shotgun blasts should be enough to destroy the [[Imp]].  Continue through the door.
-The next room (where you first found the scientist calling for help) has an imp coming around the corner, followed by two zombies.  At the end of the corridor, there is a zombie hiding behind a pillar with planted armor shards, and an imp that attempts to flank you from behind.
-Nothing in the platform overlooking the service bridge room.
-A health station to the left with 50 health. But on the ground floor, there is an imp that jumps from behind the first corner, followed by a zombie behind a pillar. Continue to the next room.
-Nothing in the plasma filter room. Continue left (as the door on the right was busted by an imp.)
-Nothing in the convergence chamber 2, but an Imp will perform a jump attack shortly after opening the exit door.  After defeating the imp, walk backwards into the next room.
-A z-sec attacks from the convergence chamber.  Once eliminated, you can look at the storage cabinet, code 531.  When you approach, there is one imp from the crawlway on the left path.  Proceed to Convergence Chamber 1.
-Convergence Chamber 1 is only a jump scare.
-Where you met the mysterious scientist that wouldn't tell you what's going on, an imp will break out of the stairs on the left.
-You should now return to the crane room - an imp climbs from the rail on the opposite side.   When you approach the stairs, the crane will break, dropping heavy materiel onto the stairs.  Head up, and an imp will attack from the security checkpoint, which you should enter.
-Defeat the Z-Sec stationed there, heal from the health station, and head to the elevator.  The last enemies are one Z-Sec coming from the opposite side, one Imp that drops from the ceiling in the elevator room, and one pistol Z-sec in the elevator itself.
 ==[[PDA]]s==
-* [[Daniel Young]]
+* [[PDA#Daniel Young|Daniel Young]]. Obtained by killing Daniel Young.
-* [[Mark Ryan]]
+* [[PDA#Mark Ryan|Mark Ryan]]. Obtained by killing Mark Ryan.
-* [[Grant Baston]]
+* [[PDA#Grant Baston|Grant Baston]]. Found in Energy Stabilization Unit, near a storage crate.
-* [[Frank Delahue]]
+* [[PDA#Frank Delahue|Frank Delahue]]. Found in Energy Processing, on a table.
 ==Characters==
@@ Line 77: / Line 43: @@
 * [[Bravo Team]]
-==Enemies==
+==Statistics==
-==== Former Humans ====
+===Enemies===
-* [[Zombie (Doom 3)|Maintenance Zombie]]
+Note: Includes only enemies that can be fought and killed. The enemy count on Nightmare is the same as on Veteran. There are no changes in the enemy amount in the [[Doom 3: BFG Edition|BFG Edition]].
-* [[Zombie (Doom 3)|Scientist Zombie]]
+{| {{prettytable|style=text-align: center;}}
-** [[Jonathan Ishii|Jonathan Ishii]]
+|-
-** Ian Sinclair
+|style="text-align: left;"|'''Enemy'''||'''Recruit'''||'''Marine'''||'''Veteran'''
-* [[Z-Sec|Pistol Z-Sec]]
+|-
-* [[Z-Sec|Shotgun Z-Sec]]
+|style="text-align: left;"|[[Zombie (Doom 3)|Zombie]]*||colspan="2"|18||19
-** T. Brooks
+|-
+|style="text-align: left;"|Pistol [[Z-Sec]]||colspan="3"|4
-==== Demons ====
+|-
-* [[Imp (Doom 3)|Imp]]
+|style="text-align: left;"|Shotgun [[Z-Sec]]||colspan="2"|4||5
+|-
+|style="text-align: left;"|[[Imp (Doom 3)|Imp]]||colspan="3"|11
+|}
+<small>* The zombie that attacks a scientist in Energy Processing has only 20 health.</small>
-==Weapons/Items==
+===Items===
-* [[Flashlight]]
+The item count on Nightmare is the same as on Veteran, except the med kits are absent. There are no changes in the amount of items in the [[Doom 3: BFG Edition|BFG Edition]].
-* [[Pistol (Doom 3)|Pistols]]
+{| {{prettytable|style=text-align: center;}}
-* [[Shotgun (Doom 3)|Shotguns]]
+|-
-* [[Machine Gun]]s
+|style="text-align: left;"|'''Item'''||'''Recruit'''||'''Marine'''||'''Veteran'''
-* Medkit
+|-
-* Security Armor
+|style="text-align: left;"|[[Flashlight]]||colspan="3"|1
-* Armor Shards
+|-
-* Bullets
+|style="text-align: left;"|[[Pistol (Doom 3)|Pistol]]||colspan="3"|2
-* Shells
+|-
-* Clips
+|style="text-align: left;"|[[Shotgun (Doom 3)|Shotgun]]||colspan="3"|4
-* Adrenaline
+|-
-* Air Canisters
+|style="text-align: left;"|[[Machine gun]]||colspan="3"|2
-* Plasma Cell
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Bullets|Bullets]] (small)||15||colspan="2"|13
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Shells|Shells]] (small)||colspan="3"|14
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Shells|Shells]] (large)||2||colspan="2"|1
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Clip|Clip]] (small)||colspan="3"|2
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Clip|Clip]] (large)||colspan="3"|1
+|-
+|style="text-align: left;"|[[Ammo (Doom 3)#Cells|Cells]] (small)||colspan="3"|2
+|-
+|style="text-align: left;"|[[Supplies (Doom 3)#Med kits|Med kit]] (small)||23||18||15
+|-
+|style="text-align: left;"|[[Supplies (Doom 3)#Med kits|Med kit]] (large)||colspan="3"|2
+|-
+|style="text-align: left;"|[[Supplies (Doom 3)#Armor|Armor shard]]||83||76||73
+|-
+|style="text-align: left;"|[[Supplies (Doom 3)#Armor|Security armor]]||colspan="3"|3
+|-
+|style="text-align: left;"|[[Adrenaline]]||colspan="3"|1
+|-
+|style="text-align: left;"|[[Supplies (Doom 3)#Air canisters|Air canister]]||colspan="3"|3
+|}
+There are also 4 [[Supplies (Doom 3)#Health stations|health stations]] on the level: two of them have 100 health in reserve, one has 50, and another has 80 (in BFG Edition all health stations have 100 health).
-==Cabinets==
+==Locker codes==
+<div class="dw-div-dl">''For the sources of the codes, see [[Doom 3 locker codes]].''</div>
+* '''Storage locker #023 - Supplies''': ''531''. Contains: ''med kit (small), shells (small), armor shard x3''.
-* '''Cabinet #023:''' ''531'' - Grant Bastion's PDA.
+==Secrets==
+* In Underground Security (the first room), there are two armor shards on a hidden ledge in the corner to the left of the entrance where the pipes are (one needs to climb those pipes to reach them).
+* In Underground Junction (the crane area), one can climb into crane cabin and find shells and two armor shards there. To reach the platform from which the crane can be accessed, the player needs to go downstairs in underground junction and find a cable that leads to that platform, which is located behind one of the pillars (there's a hidden med kit there). Once the platform is reached, the crane has to be turned to the load position by clicking on a nearby control panel. Note that after the invasion the crane becomes inaccessible because the control panel is broken. In the same platform there is a door to the maintenance storage. It's locked before the invasion, but can be opened after, from the security checkpoint (see below). There's another armor shard there, on the top of two boxes.
+* In Maintenance Area CS1, there are two armor shards hidden behind the stairs, and more on top of the machine that C. Rodgers repairs (can be access by jumping on crates then on pipes). These items are inaccessible after the invasion, due to the whole room being wrecked.
+* In Energy Processing, there are some armor shards below the floor plates.
+* In Energy Delivery, the player can climb below the bridge using a ladder nearby, and access bullets, a med kit and armor shards.
+* In Maintenance Area PD1, there are shells and armor shards below the stairs that can be reached by carefully jumping onto the adjacent pipe.
+* In Mars Surface there are an armor shard, an adrenaline and a air canister lying behind the airlock the player first comes from. Also here, one can climb onto the hill to the left of the opposite airlock to access a clip, armor shards and one more air canister.
+* In Old Comm Storage, some armor shards and a med kit can be found on the shelves to the right of the airlock.
+* In Old Comm Main, some bullets (and a med kit on Recruit) can be found on the tables (hard to see because of darkness).
+* In the room with Frank Delahue's PDA (Energy Processing), there are bullets, shards, and a med kit on a ledge near the table, and two more shards on a tall blocky machine nearby (both can be reached by stacking crates that are lying nearby). In the same room, the player can walk on a pipe to find another ledge with a med kit and shards.
+* In EP Aerobic Stabilizer, there's a large pipe that can be climbed under, and behind it a med kit and two armor shards can be found.
+* In EP Control Unit, shells and a med kit can be found under the floor (a ladder can be used to climb back up).
+* In the room where the player first encounters an imp (also called EP Aerobic Stabilizer), there are a med kit, shells and armor shards on the table behind the stream of fire emitting from the gas pipe. To access it without taking damage from the fire, the player needs to input a failure code into the first control panel in the next room the player has go through, to shut down the gas leak. The code is 842, and it can be obtained by listening to one of the audio logs from Frank Delahue's PDA.
+* In the same room where the player can shut down the gas leak, the player can also use the third control panel to open a maintenance hatch nearby for some shells and another med kit
+* After the player passes through the catwalk above the folding bridge and enters the next room (Energy Processing), there are hidden bullets to the immediate right, on a blocky machine.
+* In Energy Stabilization Unit the player is attacked by a shotgun Z-sec upon entering it. After that, if the player goes a few rooms back, they will find a closet from which the Z-sec emerged and some shells and armor shards in it.
+* In Underground Security where the player needs to use a control panel to open access to the exit elevator, the same control panel has additional access options which can be revealed by pressing the "Mars City Sublevel Access" button below. There the player can open the exit locker which contains the first machine guns, shotguns and clips, as well as unlock the door to maintenance storage. To access the maintenance storage the player has to go to the isolated platform with the crane (see above). The maintenance storage has a health station, bullets, early cells for the plasma gun, and armor shards (on the crates).
 ==Trivia==
+* On the Nightmare difficulty, you can kill the civilians to get an early charge for the Soul Cube.
+* At one point, the player will find a scientist being attacked by a zombie on a floor above them. If the player saves the scientist by shooting the zombie, later on they will find an opened (but broken) storage cabinet with health and armor in it. If the player doesn't save the scientist, the same cabinet will be closed with no way of opening it.
-*When you enter the "Energy Processing" room where you saw the scientist complaining to the maintenance guy earlier, after you kill the imp, there's a zombie hiding behind one of two pillars. Behind those pillars is a closet with shells and armor shards that never opens. The only way to see it is with the "noclip" cheat.
+==Gallery==
-* On nightmare difficulty, you can kill the civilians to get an early charge for the soul cube.
+<gallery mode="nolines" widths="230px" heights="172px">
+Mars City Underground Start.png|Underground Security (starting area).
+Mars City Underground Crane.png|Underground Junction.
+Mars City Underground Surface.png|Mars Surface.
+Mars_City Underground Old Comm Building.png|Old Comm Building.
+Mars City Underground Invasion.png|Beginning of the Hell invasion.
+Mars City Underground Imp Door.png|Imp breaks a door.
+Mars City Underground Bridge.png|Energy Delivery.
+Mars City Underground Energy Processing.png|Energy Processing.
+Mars City Underground Hallway.png|EP Control Unit.
+Mars City Underground Imp.png|Imp introduction.
+Mars City Underground Plasma Collector.png|Energy Processing, plasma collector room.
+</gallery>
 == External links ==
-* Walkthrough video by WoopzillaWalkthrough ([http://www.youtube.com/watch?v=4eJe4QKUaJs part 1]; [http://www.youtube.com/watch?v=X-DW-Ilh9ng part 2]) on YouTube.  [[Skill level#Doom 3 skill levels|Veteran]] difficulty; part of a full game run.
+* Walkthrough video by WoopzillaWalkthrough ([https://www.youtube.com/watch?v=4eJe4QKUaJs part 1]; [https://www.youtube.com/watch?v=X-DW-Ilh9ng part 2]) on YouTube.  [[Skill level#Doom 3 skill levels|Veteran]] difficulty; part of a full game run.
 [[Category:Doom 3 levels]]
 [[Category:Levels by name]]