Hell

Hell is a cornerstone element of the Doom universe. It is the source of the demonic invasion in the games. It has a significant presence in many levels, and is the setting of parts of Doom, Doom II, Final Doom and Doom 3.

Overview
Typical features of Hell in these games include copious numbers of mutilated bodies, some apparently still alive and presumably of the damned, and scatterings of Satanic iconography.

In every Doom game Hell is depicted as having developed (or stolen from Earth and made quick use of) biocybernetics, implanting modern and futuristic weapons into many of its demons, in fact the cyberdemon and the spiderdemon are both powerful demons with mechanical and organic body parts, and the icon of sin appears to be an enormous, partially mechanical demonic head, though Doom II's endgame text indicates it has a suitably massive body as well.

Demonic possession
"Zombies" in Doom are often regarded as "former" humans possessed by demons from Hell. In Doom 3 it is demonstrated that both dead and living humans can be possessed, but in the Doom novels, where Hell is not a part of the story, it is indicated that only dead humans can be made into zombies, and the Doom Bible had possession happen to living but sleeping humans.

Access to Hell
In the games Hell is discovered following experiments in teleportation technology, and during gameplay Hell is only accessible by long-distance teleporters or gateways. In the original Doom teleporters notably have Satanic symbols on them. In Doom 3, it transpires that teleporter technology was derived from documents left behind by an ancient Martian race.

Hell in Doom is heavily based on the religious concept that "bad" people spend eternal damnation in Hell after death. This is indicated in the Doom II endgame text, "You wonder where bad folks will go when they die now," and again in The Plutonia Experiment's endgame text, "Hell has gone back to pounding bad dead folks instead of good live ones." However, the player is not visibly sent to Hell when he dies: the player must continue the game from the beginning of the level, or from a saved game.

Because one cannot physically travel to Hell without the aid of some sort of gateway, Hell's actual location is never revealed, though it is indicated by the Doom FAQ and by the unusual behavior of the environment in Hell in Doom 3 that it is not a part of our universe but rather another dimension entirely.

Differences between games
While the major Doom games all depict Hell, the theme changes slightly between games. The variations between Doom and Doom II are based mainly on levels created by different designers. Doom 3's Hellish atmosphere departs more strongly from the original games.

Doom
The original Doom's Episode 3, Inferno, entirely takes place in Hell, where it is depicted as predominately brimstone-covered with a fiery sky, complete with a demonic cathedral and pools of blood. Walls and floors occasionally appear to be made from body parts including human skulls, intestines, spines and skin. In the PlayStation version, Hell's sky is filled with flames.

The game's box art and the ending screen for The Shores of Hell both depict rocky, barren landscapes.

Thy Flesh Consumed takes place between hell and Earth. This is indicated by the fact that to reach it, you had to beat inferno, and you are not yet on earth.

Deimos
In the original Doom, Mars's moon Deimos provides the first link between here and Hell.

In the storyline approaching the beginning of Doom, military experiments are conducted between the gateways at UAC facilities on Phobos and Deimos. Something went wrong, and "soon afterwards, Deimos simply vanished from the sky."

Deimos's mysterious absence is referred to in Knee-Deep in the Dead's ending text, after the player steps through the gateway at the end of E1M8: Phobos Anomaly: "It...looks like the lost Deimos base." It is later revealed at the end of Episode 2, The Shores of Hell, that the entire moon had somehow been transported to Hell. The gateways, still functioning between Phobos and Deimos, provided the first entryway into Hell.

Doom II
Doom II's Hell levels are often closer to subverted human buildings, with the exception of the last three levels. The sky in these levels (where there is any) contributes heavily to the Hellish atmosphere.

Doom 3
In Doom 3, the player ventures into Hell to obtain the Soul Cube. Hell is largely a claustrophobic and cavernous plane with crimson blood sky (it also resembles outer space to some extent), both dark and fiery (although "outdoor" sections do appear). Most time in Hell takes place in a large castle-like area, finished with huge stone bricks, broken cell gates, glowing Satanic glyphs and pentagrams, and huge oceans of magma. The conventional rules of physics are frequently violated. Unlike in Doom, the atmosphere in this Hell is almost constantly noisy, typically with the crying and moaning of damned souls and extreme sizzling and bubbling of hot magma.

Doom without Hell
One of the primary criticisms of the Doom novels is that Hell was cut out and the demons became aliens genetically engineered to scare humans instead.

A similar criticism was aimed at the Doom movie, where the monsters were humans mutated by a Martian gene splicing experiment, and universally lacked the projectile attacks of their game counterparts.