In December 1993 Intel sent a memo round the company banning a game from its networks. Several of its subnets had stopped working at lunchtime, Computer Gaming World reported, “as employees raced to get in a game of multiplayer DOOM DeathMatch”. Other large companies issued bans of their own. Nobody had paid for the copies that caused the trouble. id Software gave away the first of Doom’s three episodes and asked people to pass it on, and the game spread through bulletin boards, university FTP sites and office networks faster than any shop could have sold it.
Doom was a first-person shooter: you saw the world through a space marine’s eyes and fought your way out of a research base overrun by creatures from Hell. id had made the idea famous the year before with Wolfenstein 3D. Doom added stairs, lifts, flickering lights and monsters firing down from balconies, and it let four players share the same maze.
Fast facts
- Developer and publisher: id Software, Mesquite, Texas. The full game was ordered from id by phone, on 1-800-ID-GAMES.
- Released: 10 December 1993, when the shareware episode went out over the internet.
- Price: $40 for all three episodes; the first, Knee-Deep in the Dead, was free to copy.
- Team: programming by John Carmack, John Romero and Dave Taylor; levels by Romero, Sandy Petersen and, until August 1993, Tom Hall; art by Adrian Carmack and Kevin Cloud; music by Bobby Prince.
- Needed: a 386DX or better (a 486 was recommended), 4MB of memory and VGA graphics.
- Multiplayer: up to four players over an IPX network; two over a modem from version 1.2.
- Source code: released on 23 December 1997, and relicensed under the GNU General Public License in 1999.
Eleven months
id finished Wolfenstein 3D in May 1992 and began Doom properly in January 1993, when Tom Hall wrote a press release promising technology nobody had seen. Hall also wrote the design document, the “Doom Bible”, but he left in August 1993 over creative differences and went to Apogee. id hired Sandy Petersen, the designer of the tabletop role-playing game Call of Cthulhu, to help finish the levels, and Dave Taylor joined as a programmer. Fabien Sanglard, who has written the standard account of the engine, counts fourteen people involved by the time the shareware version was ready for Christmas.
They built it on NeXT workstations, not PCs. Romero later recalled writing the level editor, DoomEd, in Objective-C, and seeing the game on monitors at 1120×832. Carmack’s rendering code ran in a window under NeXTSTEP for debugging and was recompiled to run full-screen under DOS.
What the engine could and could not do
Carmack set out the engine’s limits himself, in an essay for the 1994 strategy guide DOOM: Survivor’s Strategies & Secrets. A Doom map is “a two-dimensional arrangement of lines representing walls, and flat floors and ceiling of variable heights”. Each area of floor, called a sector, had its own floor height, ceiling height and light level, so a map could have stairs, pits, raised platforms and dark rooms next to bright ones. Walls could meet at any angle, where Wolfenstein 3D’s sat on a square grid. But “Doom cannot draw sloping floors, overlapping walkways, or tilted walls”. One room could never sit above another.
Those limits kept it fast. Because the world was flat in plan, Carmack could reduce the question of which wall hides which to a two-dimensional problem and answer it with a binary space partitioning tree, worked out once by a separate program when the map was built. The cost was that walls could not move sideways during play: “Thats why there are no swinging doors in Doom.”
Players did not see the limits. Computer Gaming World praised the “fully-functional stairs, elevators, and moving platforms”, and Edge told readers to “go back and play Wolfenstein and you’ll laugh at the horrible 2Dness of the 3D perspective”. The view bobbed as the marine ran, which the American magazine called “a wonderful touch that’s almost too natural to notice”.
Shareware on the shelves
The shareware episode, nine levels on two floppy disks, ended with a screen telling players how to order The Shores of Hell and Inferno. id went further than giving it away online. Jay Wilbur, id’s chief executive, told shops they could sell boxed copies of the free episode and keep all the money. Romero recalled that the title screen said “Suggested retail price $9”, and that in 1994 a computer superstore might have “ten different boxes of doom”, all of them the same shareware game. Edge called it “a marketing coup”: ship a game this playable “with the message, ‘please distribute like crazy’ and you’re guaranteed a big audience”.
Nobody knows exactly how many copies sold. Sandy Petersen said the game “sold a couple of hundred thousand copies during its first year”. Sanglard’s history puts the total at more than two million, with an estimated 20 million installations of the shareware.
DeathMatch
Romero named the mode. “For the first time we were putting multiplayer into our game with a mode I called Deathmatch because that name just made sense,” he wrote in 2018. Doom let up to four players play together over an IPX network, cooperatively or against each other, and version 1.2 added modem play at 9,600 baud or faster.
Computer Gaming World’s reviewer, Bryan Walker, thought the DeathMatches “may be the most intense gaming experience available today”, and admitted that one had made him break his joystick. The first release was hard on networks. It sent its data as broadcast packets, which every computer on a network had to stop and read, so a few games at once could bring a company’s servers to a crawl. Jay Wilbur told the magazine that version 1.2 would send data only between the machines playing. Playing Doom with friends usually meant carrying the computers into one room; see LAN parties. The first tournaments followed, described in the origins of esports.
What the reviewers said
Computer Gaming World called it “a virtuoso performance” and “what is probably the best action game to date”. Its only complaint was the ending: the final monster “was too easy to kill”.
Edge in Britain was more guarded. It watched “hundreds of grown men start acting like they’ve never seen a videogame before” and said it had “no intention of joining the rabble mindlessly praising Doom beyond its worth”. It admired the lighting, which made walking through a flashing computer room “a seriously intense videogame experience”, but found the gameplay “as narrow as it gets”. Its review ended with a line readers still quote against it: “If only you could talk to these creatures, then perhaps you could try and make friends with them, form alliances… Now, that would be interesting.”
By 1996 the argument was over. Computer Gaming World ranked Doom fifth in its 150 best games of all time and third among the most innovative, because it “accelerated the first person action trend by putting monsters right in your face and on your network”. In the same issue it described the action genre as “an industry dominated by DOOM-clones”. “Doom clone” was the name for the genre until “first-person shooter” replaced it.
WADs, mods and demos
id kept almost everything except the program itself in one file, DOOM.WAD, and let a player’s own WAD files replace any map, sound or picture in it. Players wrote their own editors and made thousands of levels; the modding and total conversions entries tell that story. The game could also record a play-through as a small demo file, which is where speedrunning began.
Doom II and the ports
Doom II: Hell on Earth followed in 1994, sold in shops. The first game was converted, with cuts and changes, for the Atari Jaguar and Sega 32X in 1994, the Super Nintendo and PlayStation in 1995, the 3DO in 1996 and the Sega Saturn in 1997.
Released source code
id released the source code of Doom on 23 December 1997. It was not quite the code that had shipped. Bernd Kreimeier had planned a book explaining the engine and had cut the code down to the Linux version, because the DOS version used a licensed sound library, DMX, whose code id could not publish. The book was abandoned, and Kreimeier released his cleaned-up code with id’s blessing. Carmack’s note began: “Here it is, at long last. The DOOM source code is released for your non-profit use. You still need real DOOM data to work with this code.”
On 3 October 1999 the code was relicensed under the GNU General Public License, version 2 or later, which allows commercial use as long as the source is shared. id publishes it today in its id-Software/DOOM repository on GitHub. Hundreds of “source ports” grew from it, among them Doom Legacy, Boom, PrBoom, ZDoom, GZDoom and Chocolate Doom, which let the original levels run on modern systems. The game data itself stayed commercial: to play the original episodes you still need id’s WAD files.
Later Doom
id returned to the series with Doom 3 in August 2004, a slower horror game. Doom (2016) went back to speed and sold two million copies on PC by July 2017. Doom Eternal followed in 2020 and Doom: The Dark Ages in 2025. In 2024 id re-released the first two games together as Doom + Doom II.
Sources
- Bryan Walker, “DOOM, DOOM, DOOM, DOOOOOM!”, Computer Gaming World issue 116, March 1994, pp. 37–39: the review, the $40 price, the designers, system requirements, the episodes, network and modem play, the quotations. News, p. 14, same issue: “Intel Bans DOOM!”, the broadcast-packet problem and Jay Wilbur on version 1.2.
- Computer Gaming World issue 113, December 1993: buying-guide entry (price, shareware first episode, 1-800-Id-Games).
- Edge issue 7, April 1994, pp. 60–63: Doom review (shareware distribution, “a marketing coup”, “please distribute like crazy”, the comparison with Wolfenstein 3D, the quotations).
- Computer Gaming World issue 148, November 1996: “The Top 150 Games of All Time” (Doom fifth), “The Most Innovative Games of All Time” (Doom third, p. 102), and “an industry dominated by DOOM-clones” (Crusader: No Remorse, 38th).
- John Carmack, essay in Jonathan Mendoza, DOOM: Survivor’s Strategies & Secrets (1994), reproduced in Sanglard (below), appendix G.1: the engine’s capabilities and limits, the BSP tree, “no swinging doors”, development on NeXTSTEP.
- Fabien Sanglard, Game Engine Black Book: DOOM (2018): John Romero’s foreword (DoomEd, naming Deathmatch, Tom Hall’s departure, Sandy Petersen and Dave Taylor); chapter 4 (the team of fourteen, the January 1993 start, Hall’s departure, sectors, distribution, Jay Wilbur’s and Romero’s accounts of shops selling the shareware, the Wisconsin FTP release on 10 December 1993); section 5.1 (the source code release and Kreimeier’s role); chapter 6 (console ports and their years); the epilogue (sales estimates, Petersen’s first-year figure, Doom II, Doom 3, Doom (2016), source ports); appendix E (Carmack’s release note, 23 December 1997). The “more than two million copies” and 20 million installation figures are from the book’s introduction.
- id Software,
DOOMrepository on GitHub (web, secondary): Carmack’s 1997 release note and the GPL-2.0 licence. https://github.com/id-Software/DOOM - “Doom engine”, Wikipedia (web, secondary): the relicensing under the GNU GPL v2 or later on 3 October 1999. https://en.wikipedia.org/wiki/Doom_engine
- “id Software”, Wikipedia (web, secondary): Doom Eternal (2020), Doom + Doom II (2024) and Doom: The Dark Ages (2025). https://en.wikipedia.org/wiki/Id_Software