DOOM is a first-person shooter computer game released by id Software on December 10 1993. Featuring huge advances in gameplay and graphics compared to its predecessor Wolfenstein 3D, it was widely regarded as a quantum leap in video game technology at that time.
Doom consisted of three episodes with nine levels each; eight of these levels needed to be completed to finish an episode, while the ninth one was a secret level that could be accessed from within the first seven. The first episode, "Knee-deep in the dead", was released as shareware, while the second and third ("Shores of Hell" and "Inferno") were only available in the commercial version.
The game was released (with varying degrees of modification) for many systems and consoles, which included the following: PC, Super NES, Sega 32X, Sony PlayStation, Game Boy Advance, Atari Jaguar, Sega Saturn, Nintendo 64 and 3DO. An arcade version using a "virtual reality headset" (an LCD screen an inch from the player's face) also existed; furthermore, a port to the Nokia 7650 and 9210 cell phones is available from WildPalm, and a port to the Game Park 32 (a korean hand-held similar to the Game Boy Advance) can be downloaded here from GBAx.com.
Doom III is expected to be released in 2003, with a completely new engine; however, classic Doom retains a loyal following until today as well, and it is credited with making the first-person shooter a genre of computer game in its own right.
Technology
Doom introduced to a wide audience the concept of playing over a network together ("co-operative mode") or against each other ("deathmatch mode") into the genre of first-person shooter games. It was not the first first-person shooter to do so, though; a game called MIDI Maze on the Atari ST did so in 1987, using the MIDI port built into the ST.
The software method used to present a 3D visual experience was clever, but sacrificed generality for speed. Levels were two-dimensional; and even though each section could have a different height, no part of the map could extend above or below another part. Careful level layout kept this constraint from being apparent to the player, giving the impression of an actual three-dimensional level, but these constraints also made the method unsuitable for generalized 3-dimensional applications such as CAD. They were, however, quite workable for a pre-built game environment, where the designers could dance around the limitations, and the commercial success of the game, as well as the abundance of third-party levels and add-ons that followed, demonstrated that these constraints did not detract from the gameplay experience.
Sequels
A sequel, DOOM II: Hell on Earth, was released on October 10 1994. Doom II consisted of thirty regular levels, plus two "secret" levels, which nearly duplicated episode 1 level 1 and episode 1 level 9 of Wolfenstein 3D. The engine and gameplay were the same as Doom, however there were some different weapons and monsters. The two secret levels were missing from the version marketed in Germany because they depicted Nazi symbols, illegal under german law (see the article on Wolfenstein 3D for more information).
In 1995, a new version of Doom 1 was published; titled Ultimate Doom, this release included the three original episodes as well as a new, fourth one, named "Thy flesh consumed". Another year later, in 1996, two new 32-level episodes for Doom II were released, "The Plutonia Experiment" and "TNT: Evilution", both developed for id Software by Team TNT. None of these were available as shareware; they were only sold as commercial versions.
The Doom engine
The Doom engine (the core of the game software), as well as the game itself, continued to be developed even after its initial release; there were a total of 9 versions, from the earliest 1.0 to the final 1.9 release. Notable among these was the 1.1 release, which featured the ability to run Doom on three computers in single player mode, adding left and right screens for the player; this feature, though, was removed from version 1.2 and the following ones again.
Early history
Four pre-release versions also exist, consisting of three alpha and one press-release version. The first alpha, 0.2, was released on February 4 1993; it consisted of a single level, but was not yet playable in the sense that later versions were. Two months later, on April 2, alpha 0.4 featured a new logo, a few more, new levels (including a very early version of E2M2 from the final game), and finally, on May 22, version 0.5 was done. The press-release version, containing three levels that looked much like the final ones was released on October 4 for journalists only; it was programmed to stop working after October 31. All of these versions have been made available by id Software, and can be downloaded from http://www.doomworld.com/classicdoom/info/shareware.php.
The game engine was licensed to several other companies as well, who released their own games based on it, including Heretic, Hexen, Strife and HacX.
Source Ports
The source code of DOOM was published by id Software in 1997 under a proprietary license. The game was then ported to various other operating systems. In late 1999, the source code was re-released under the terms of the GPL. Several ports have been developed, the most notable being TeamTNT's Boom, Lee Killough's Marine's Best Friend (MBF), and later on, PrBoom, Eternity, jDoom, ZDoom, Doom Legacy, ZDoomGL, ZDaemon, and Skulltag. Most ports contain considerable changes to the game, including bug fixes, the removal of engine limitations, and various new features.
Competitors
Doom spawned many imitators and competitors, some based on the game engine licensed from id (see below). Duke Nukem 3D, a more tongue-in-cheek game based on Ken Silverman's 'build' engine, and Apogee's Rise of the triad were its principal rivals. Id Software re-designed the game engine and released the sequel to Doom, Quake, in 1996. Quake's success mirrored that of Doom for the remainder of the 1990s, though the success of competitor Unreal Tournament seduced a large segment of Quake's audience away.