All of the maps in this episode are credited to Sandy Petersen, though many of them were first started by Tom Hall. The episode takes place in the UAC installations on Deimos, which is being overrun and infested by the demonic forces. To show this, its levels generally resemble UAC facilities that have been partially altered by the demonic invaders. The sky used for the background consists of mountains against red clouds. In the end Doomguy fights Cyberdemon as a boss and teleports to Hell.
- E2M1: Deimos Anomaly
- E2M2: Containment Area
- E2M3: Refinery
- E2M4: Deimos Lab
- E2M5: Command Center (Exit to secret level)
- E2M6: Halls of the Damned
- E2M7: Spawning Vats
- E2M8: Tower of Babel (Cyberdemon is the boss)
- E2M9: Fortress of Mystery (Secret level)
End of Episode Message
You've done it! The hideous Cyberdemon lord that ruled the lost Deimos moon base has been slain and you are triumphant! But... where are you? You clamber to the edge of the moon and look down to see the awful truth.
Deimos floats above Hell itself! You've never heard of anyone escaping from Hell, but you'll make the bastards sorry they ever heard of you! Quickly, you rappel down to the surface of Hell.
Now, it's on to the final chapter of Doom! -- Inferno.
The Compet-n records for the episode are:
|UV Episode||04:22||Adam Hegyi||1999-06-25||ep2-0422.zip|
|NM Episode||04:52||Drew "stx-Vile" DeVore||2004-05-18||e2nm0452.zip|
|UV Max Episode||29:11||Radek Pecka||2001-06-10||ep2-2911.zip|
|NS Episode||12:40||Drew "stx-Vile" DeVore||2002-10-19||e2ns1240.zip|
|UV -fast Episode||36:55||Radek Pecka||2002-08-29||e2fa3655.zip|
- The episode's intermission screen changes from level to level, showing how E2M8: Tower of Babel is gradually built by the forces of Hell as the marine advances. It begins as a small nub upon completing E2M1: Deimos Anomaly, but appears as fully built upon completing E2M7: Spawning Vats.
- Initially, the episode's secret level is not visible on the map. It fades in only after the player discovers the secret exit to it, and then disappears again after it is completed. Its location on the map is in very close proximity to the Tower of Babel's construction site.
- Many of the episode's levels feature UAC locales that have alterations or additions of hellish origin. For example, while most buildings still use human-made keycards for locked doors, some others use demonic skull keys. E2M3: Refinery includes keycards for the player to pick up, but also has some skull-marked door frames. Some switches found in the levels are UAC-style push buttons, while others appear to be of demonic nature. To a certain degree this is because the levels were originally designed to be plain UAC facilities, as seen in the alpha versions of the game, but were later moved to a more hellish environment. This decision was made more believable by having Deimos teleported to a location over Hell's surface at the beginning of the game. Due to this, fan-made levels that mix techbase and demonic textures are sometimes referred to as Shores of Hell levels.
- Similarly, the level names suggest that only four buildings (levels two through five) are UAC-built, and that the others are new hellish buildings (brand-new, in the case of the Tower of Babel).
- In comparison with the previous episode, many maps of this episode have quite high ratios of summary monster hitpoints to amount of ammo pickups available to the player. This is because of increased difficulty, and also because the number of former humans (who drop their guns when killed) is smaller, whereas the majority of enemies are hellspawn, who drop nothing.
- The plasma gun appears in all of the levels, with the exception of Tower of Babel.
- Monsters making their initial appearance in the episode are the Cacodemon, Lost Soul, and Cyberdemon.