Mars



Mars is the fourth planet from the sun in the Solar System.

Classic Doom
Doom's action takes place on Phobos and Deimos, the two moons of Mars, although in the introductory story the protagonist is initially stationed on Mars itself, where the UAC has set up nuclear waste disposal facilities. The military, of which the player character is a part, has loaned the Martian moon bases from the UAC to perform research on teleportation technology.

It is often assumed the setting of the game is on Mars, but in fact none of the events take place on the planet. In fact, the player never ventures to the surface of the planet in any of the games or episodes. Doom 64 may take place on the planet's surface, but the game is ultimately vague about its setting and refers only to it being under a policy of "planetary quarantine," maintained due to apocalyptic levels of radiation.

Doom 3 and expansions
In Doom 3, Resurrection of Evil, and The Lost Mission, the action is set directly on Mars, in the fictional Mars City. The player is required to venture onto the barren surface of Mars a number of times during Doom 3, and must fight off demons while topping off his oxygen supply via collectible tanks. Although the planet is portrayed as being realistically inhospitable, a decision was made early on to increase Mars' gravity to match Earth's for gameplay reasons.