Making of Doom

The making of Doom, id Software's computer game released on December 10, 1993, began in late 1992. Doom raised the bar for realism in video games with its then-advanced 3D graphics &mdash; central to its success was the new game engine by John Carmack, whose main advances included texture mapping of all surfaces, variable light levels, and floors at varying altitude. The world in Doom materialized through the artwork of Adrian Carmack, Kevin Cloud and Gregor Punchatz, and the level design of John Romero, Sandy Petersen and Tom Hall.

Doom evolved significantly during its development. Originally planned to feature an intricate plot, its gameplay instead gradually turned to focus on fast action and violence. Conflicts surrounding this development led to the resignation of Tom Hall, who had written the Doom Bible, the game's initial design document.

Conception
Following the successful release of Wolfenstein 3D in May 1992, most of the id Software team set out to finish the sequel Spear of Destiny. Since this game used the same game engine as Wolfenstein 3D, lead programmer John Carmack could use the time to begin work on the company's next-generation graphics engine. With significant effort, choosing to isolate himself from the rest of the team for a long period of time in order to avoid distractions, he implemented various new features, including diminishing light and texture-mapped floors and ceilings. He even added support for sloping floors, although this feature was later removed. The engine was not developed with Doom in mind, and in fact Doom was not the first game to make use of it; instead, Raven Software licensed an early version for Shadowcaster, which would be released before Doom in 1993.

The making of Doom began after the release of Spear of Destiny in September 1992. The initial idea was to make a movie license game based on Aliens, one of the team's favorite science fiction-action films, and some negotiations were made with 20th Century Fox. The plan was eventually ditched in order to get more creative freedom, halting the negotiations. John Carmack instead conceived of the basic theme for the game: demons versus technology. Doom was viewed to be a cross between Aliens and the team's favorite horror B-movie, Evil Dead II. The idea to include demons was also inspired by their most recent Dungeons & Dragons campaign, which had ended with demons overrunning the entire planet.

Tom Hall and the Doom Bible
The horror-tech theme was not accepted unanimously. Creative director Tom Hall instead wanted to continue the Commander Keen series with a third trilogy, but the others felt that the cartoon style of the Keen games would not do justice to the new 3D engine. Conceding defeat, he instead set out to create the new game's design document &mdash; which he titled the Doom Bible, while the others were programming and creating graphics.

Unlike Wolfenstein 3D, which had essentially been a plotless shooter game, Hall wanted Doom to have an elaborate story. The game was to take place on an alien planet called Tei Tenga, on which the UAAF (United Aerospace Armed Forces) had two military research bases. There would be five player characters with different personalities and abilities: Lorelei Chen, John "Petro" Pietrovich, Dimitri Paramo, Thi Barrett and Buddy Dacote; the game would start with creatures from hell suddenly bursting in while the five were playing cards. There would be a total of six episodes, with storylines involving traveling to Hell and back through the gates which the hellspawn used, and the destruction of Tei Tenga, for which the players would be sent to jail.

John Carmack disapproved of the detailed plot, instead conceiving Doom as a simple, action-oriented game, making the remark "Story in a game is like story in a porn movie. It's expected to be there, but it's not that important." This creative conflict, and others agreeing that Hall's levels emphasized realism at the cost of making the gameplay entertaining, finally ended with Hall being forced to resign in the summer of 1993.

The Doom Bible as such was scrapped, but several of the ideas were kept for the final game. As in the Bible, Doom starts in a military research base and features a trip to Hell and back, although Tei Tenga was replaced with Phobos and Deimos, the moons of Mars. There is only one player character, an anonymous space marine. Several of the locations, items and monsters mentioned in the Bible appear, though modified.

Some of the ideas from the Doom Bible, though discarded for Doom, showed up in later games. Instead of employing separate levels, Doom was initially supposed to use a hub system to enable a large, continuous world; in the game, the different areas would be connected by a monorail. Hubs were later used in id Software's Quake and RavenSoft's HeXen. The game would include interactive computer terminals; this first appeared in Doom 3. Tom Hall additionally used concepts from the Doom Bible in Rise of the Triad and Terminal Velocity, which he designed after leaving id Software for Apogee and 3D Realms. Also, a weapon referred as the Laser in the Doom Bible made its only appearance in Doom 64.

Programming
Doom was developed on NeXT workstations, under the NEXTSTEP operating system. The Doom game engine was programmed in C, and the editing tools were written in Objective-C. The engine was first compiled with Intel's C compiler for DOS, but later on Watcom's C/C++ compiler was used.

The bulk of the Doom game engine was programmed by John Carmack. John Romero implemented code to save and load games, interactive features such as flickering lights, doors, raising stairs and crushing ceilings. Dave D. Taylor was hired as a "spackle coder", adding things such as the status bar, sound library integration, the automap, level transitions, cheat codes, and the network chat system. The sound library, DMX, was an external piece of software created by Paul Radek, and not included in the 1997 release of the Doom source code.

The editing tools used to build the game included scripts to generate source code for monsters from definition tables, a tool to link together WAD files from data lumps, the BSP nodes builder by John Carmack, and DoomEd, the Doom level editor. DoomEd's structure and basic functionality, such as drawing lines and reading sector information, was implemented by Carmack; Romero added texture viewers and dialogs. Among the editing utilities, only the BSP nodes builder has been released to the public.

Levels
See Episodes and levels of Doom for a complete list of credits

The Doom Bible contained detailed descriptions of scenarios that were to appear in the game. Tom Hall studied real military bases to create realistic locations, such as "Recreation and Training Center" and "Supply Depot Two". He built several levels, but as they were constructed and placed in the game, the others found them banal and uninspiring. Hall's levels were mostly flat and square, like Wolfenstein 3D, and decorated with real-life wallpapers, floor tiles and office equipment. To show off the game engine's capabilities, John Romero instead began creating levels that were more abstract. The team settled for Romero's less realistic but more vivid style, which is found throughout the game's first episode, Knee-Deep in the Dead.

Romero only designed the levels for the first episode in Doom, due to being occupied with programming and other tasks. When Tom Hall resigned, an extra level designer was needed in order to complete the game on schedule, and Sandy Petersen was hired about 10 weeks before release. In those 10 weeks, Petersen finished all of episodes two and three, and one level for the first episode &mdash; 19 levels in total, of which eight were overhauled versions of levels by Tom Hall. Petersen paid less attention to aesthetics than Romero, but the others thought his levels were as fun to play.

Graphics
Adrian Carmack and Kevin Cloud were the chief artists behind Doom. Additionally, Don Ivan Punchatz was hired to create the package art and logo, and his son Gregor Punchatz created some of the monsters.

A mixed media approach was taken to the artwork. Most of the sprites were drawn by hand, but some of the characters were digitized from sculptures. These were the player character, the Cyberdemon and the Baron of Hell, all done in clay by Adrian Carmack, and the Arch-Vile, the Mancubus, the Spider Mastermind and the Revenant, created in latex and metal by Gregor Punchatz. The sculptures were photographed from five to eight different angles so that they could be rotated realistically in-game, and finally touched up, colored and animated digitally with a program created by John Carmack, the "Fuzzy Pumper Palette Shop".

The shotgun and the pistol seen in the game are photographs of toy weapons bought at Toys "R" Us; the chainsaw is a McCulloch Eager Beaver, borrowed from Tom Hall's girlfriend. The hands seen holding the weapons, and the brass knuckle fist, are Kevin Cloud's. Textures were both painted and created from scanned pictures. Among the more unusual sources, one texture was based on Adrian's snakeskin boots, and a bloody texture for the hell levels was created from a photograph of a wound on Cloud's knee.

Sound
For music and sound effects, id Software hired Bobby Prince who had previously scored Wolfenstein 3D and worked on the Commander Keen games. Initially, John Romero gave him a couple of heavy metal records and told him to create something similar for Doom. As the design of the game progressed, it was realized that this style would not be appropriate for all levels, so Prince also created some ambient tracks. The music tracks were finally assigned to the individual levels by Romero.

Several of the music tracks are inspired by parts of songs, written by famous heavy metal bands. For instance, the distinctive lead synth 'electric guitar' riff from the level E1M1 was inspired by a riff at 0:23 in Slayers's "Behind The Crooked Cross".

Although this was done without permission, none of the bands has attempted to bring legal action against id Software. According to Romero, Prince, who was previously a lawyer, "knew the legal amount of sampling that he could do without getting into trouble". Users of the Doomworld forum have compiled the following (unofficial) list:

On a side note, Prince's "borrowing" of songs was hardly limited to Doom; for instance, the title screen music from Cosmo's Cosmic Adventure was the ZZ Top song Tush, the "He's Back" song from the first level and a few other levels in Duke Nukem II is based on Megadeth's "Angry Again;" and another of the level songs, "Squeak," is based on Megadeth's "Skin O' My Teeth." 

In addition to heavy metal albums, several of the songs were inspired by the activities of the id Software team. Prince and John Carmack would often stay in the office at hours when no one else was around; "Deep Into The Code" refers to Carmack's habit of programming for long periods without leaving the computer, oblivious of his surrounding. Before sound effects had been added to the game, Romero was noted to energetically supply his own while playing, and Prince created the track "Waiting For Romero To Play" after observing the anticipation of people lining up to watch Romero in action. The final sound effects for the monsters were mixed from various animal sounds and recordings by Romero and Prince.

Pre-release versions
Four pre-release versions of Doom originally intended for testers and the press have afterwards been released to the public due to historical interest. None of the pre-release versions have sound or music.

0.2 alpha
Released in February 1993, after two months of development, this early alpha version demonstrates three of the main technological advances in Doom: texture mapping, variable light levels and non-orthogonal walls. The player can move around a small, completely flat level and press keys to change the light level and the textures. The Imp, Demon and Baron of Hell monsters are in place, but do not act or interact with the player. The heads-up display (HUD) is more complex than in the final game, including a small automap view and what appears to be a display for messages from other player characters; it is however, non-functional, most likely a placeholder. The HUD also lists three items: "Captain's hand", "Heart of Lothar" and "Sandwich", items from Tom Hall's design document for the game.

0.4 alpha
Many of the level structures from the final game are recognizable, but have significantly different textures and/or differences in layout. Lifts and doors do not move. The enemies still do not attack. The player has a rifle weapon which can be fired.

0.5 alpha
More levels are present. Notably, most of Doom II map10 is present as the sixth level. Platforms now move, and doors can be opened. The player can take damage from slime, and can die. Various items are present, and can be picked up. Health kits will heal the player, and use the graphics from Wolfenstein. Ammo clips will give ammo. Keycards and bonus (point scoring) items are also present. The enemies still do not attack. They disappear when shot. The player now has a rifle bayonet as a melee weapon, in addition to the rifle.

Press release
Functionally fairly close to the commercial release version, with three levels. The Plasma Rifle fires red shots as well as green shots. The BFG 9000 fires many such shots in a wide field in front of the player, instead of the large plasma ball and invisible rays of the release version.