Mars City Underground: Union Aerospace Subsystems

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 zombies are first seen. The Imp is introduced at a cutscene.

PDAs

 * Daniel Young (Kill Daniel to get his PDA)
 * Mark Ryan
 * Grant Baston
 * Frank Delahue

Characters

 * T. Brooks
 * Daniel Young
 * C. Rogers
 * R. Fry
 * Ian Sinclair
 * Jonathan Ishii
 * Joe
 * UAC announcer
 * Sergeant Kelly
 * Mark Ryan

Cabinets

 * Cabinet #023: 531