Doom 3 (stylized as D00M3) is a science fiction survival horror first-person shooter video game developed by id Software and published by Activision. Doom 3 was first released for Microsoft Windows on August 3, 2004. Developer Vicarious Visions ported the game to the Xbox console (also backwards compatible to the Xbox 360), releasing it on April 3, 2005. British developers Splash Damage also assisted in design for the multiplayer elements of the game.

The game is a reboot of the Doom franchise, disregarding storylines of the previous Doom video games, it is however a prequel to Doom I and II (according to the Doom RPG website they are all part of the same universe, it places Doom RPG as a sequel to Doom 3, and prequel to Doom/Doom II all starring the same marine character. Doom 3 is set in 2145 on Mars, where a military-industrial conglomerate has set up a scientific research facility to research into fields such as teleportation, biological research and advanced weapons design. However, the teleportation experiments inadvertently open a gateway to Hell, resulting in a catastrophic invasion by demons. The player, an anonymous space marine, must fight through the base and find a way to stop the demons attacking Earth.