Doom (also typeset as DOOM,^[1], and sometimes DooM) is a 1993 first-person shooter computer game by id Software that is a landmark title in the first-person shooter video game genre, and in first person gaming in general. It is widely recognized for pioneering immersive 3D graphics, networked multiplayer gaming on the PC platform, and support for custom expansions (WADs). Distributed as shareware, Doom was downloaded by an estimated 10 million people within two years, popularizing the mode of gameplay and spawning a gaming subculture; as a sign of its effect on the industry, games from the mid-1990s boom of first-person shooters are often known simply as "Doom clones". Its graphic and interactive violence^[2] has also made Doom the subject of much controversy reaching outside the gaming world. According to GameSpy, Doom was voted by industry insiders to be the greatest game of all time in 2004.^[3]

The Doom franchise was continued with Doom II: Hell on Earth (1994) and numerous expansion packs, including The Ultimate Doom (1995), Master Levels for Doom II (1995), and Final Doom (1996). Originally released for PC/DOS, these games have later been ported to many other platforms, including nine different game consoles, Rockbox firmware, and even PDAs and the Flash Player virtual machine. The series lost mainstream appeal as the technology of the Doom game engine was surpassed in the mid-1990s, although fans have continued making WADs, speedruns, and modifications to the source code released in 1997. The franchise again received popular attention in 2004 with the release of Doom 3, a retelling of the original game using new technology, and an associated 2005 Doom motion picture.