||This article's use of external links may not follow Wikipedia's policies or guidelines. (June 2010)|
||This article needs additional citations for verification. (June 2010)|
Doom WAD is the default format of package files for the video game Doom or its sequel Doom II: Hell on Earth, that contain sprites, levels, and game data. WAD stands for Where's All the Data?. Immediately after its release in 1993, Doom attracted a sizeable following of players who created their own mods for WAD files—packages containing levels, graphics and other game data—and played a vital part in spawning the mod-making culture which is now commonplace for first-person shooters. Thousands of WADs have been created for Doom, ranging from single custom levels to full original games; most of these can be freely downloaded over the Internet. Several WADs have also been released commercially, and for some people the WAD-making hobby became a gateway to a professional career as a level designer.
There are two types of WADs: IWADs (internal WADs) and PWADs (patch WADs). IWADs contain the data necessary to load the game, while PWADs contain additional data, such as new character sprites, as necessary for custom levels.
Extensibility in Doom 
When developing Doom, id Software was aware that many players had tried to create custom levels and other modifications for their previous game, Wolfenstein 3D. However, the procedures involved in creating and loading modifications for that game were cumbersome.
John Carmack, lead programmer at id Software, designed the Doom internals from the ground up to allow players to extend the game. For that reason, game data such as levels, graphics, sound effects and music are stored separately from the game engine, in "WAD files". This allowed players to make their own data without any modification to the engine itself. According to Doom's initial design document, WAD stands for "Where's All the Data?".
The idea of making Doom easily modifiable was primarily backed by Carmack, a well-known supporter of copyleft and the hacker ideal of people sharing and building upon each other's work, and by John Romero, who had hacked games in his youth and wanted to allow other gamers to do the same. Not everybody in the id Software crew was happy with this development; some, including Jay Wilbur and Kevin Cloud, objected due to legal concerns and in the belief that it would not be of any benefit to the company's business.
Utilities and WADs appearing 
Immediately after the initial shareware release of Doom, on December 10, 1993, enthusiasts began working on tools to modify the game. On January 26, 1994, Brendon Wyber released on the Internet the first public domain version of the Doom Editing Utility (DEU), a program created by Doom fans which made it possible to create entirely new levels. DEU continued development until May of the same year. It was made possible by Matt Fell's release of the Unofficial Doom specifications. Shortly thereafter Doom enthusiasts became involved with further enhancing the DEU program. Raphaël Quinet spearheaded the program development efforts and overall project release while Steve Bareman lead the documentation effort and creation of the DEU Tutorial. More than 30 other people also helped with the effort and their names appear in the README.1ST file included with the program distribution. Yadex, a fork of DEU 5.21 for Unix systems running X, was later released under the GNU/GPL license. (Carmack additionally released the source code for the utilities used to create the game, but these were programmed in Objective-C, for NeXT workstations, and were therefore not directly usable for most people, who were PC users.)
Soon, countless hobbyists were building custom WADs and sharing them over AOL and CompuServe forums, and other Internet-based channels. Many of the WADs were in the style of the stock game, others were based on TV series, movies, or original themes. Some of the id Software staff have revealed that they were impressed by some of the WADs; John D. Carmack later said the following about a Star Wars-themed modification:
I still remember the first time I saw the original Star Wars DOOM mod. Seeing how someone had put the death star into our game felt so amazingly cool. I was so proud of what had been made possible, and I was completely sure that making games that could serve as a canvas for other people to work on was a valid direction.
Even though WADs transformed the game by replacing graphics and sounds, they were somewhat limited; much of the game's behavior, including the timing and power of weapons and enemies, was hard-coded in the Doom executable file and impossible to alter from WADs. One program called DeHackEd addressed this fact by letting users modify parameters inside the Doom executable itself.
Commercial WADs 
Around 1994 and 1995, WADs were distributed primarily through BBSs and via CD collections found in computer shops or bundled together with instruction guides for level creation (in later years Internet FTP servers became the primary method for obtaining these works). Although the Doom software license required that no profit be made from custom WADs, an id Software member claimed to have taken some measures against distributors of CD-ROM compilations of WADs, some WAD sets and shovelware bundles were nonetheless obtainable for a price at certain outlets.
The id Software team was at the time working on their next game Quake, using new technology, but started side projects picking up some of the most talented WAD makers from the community to create official expansions and compete with the unauthorized collection CDs. The team produced the 21 Master Levels, which on December 26, 1995, were released on a CD along with Maximum Doom, a collection of 1,830 WADs that had been downloaded arbitrarily from the Internet. In 1996, Final Doom, a package of two 32-level sets created by TeamTNT, was released as an official id Software product.
Additionally, a handful of first-person shooter games released at the time used the Doom engine under a commercial license from id Software, as such essentially being custom WADs packaged with the Doom engine. An example is the 1997 release, HacX.
In addition to the many people who contributed to commercially released WADs, some authors became involved with the development of other games:
- Tim Willits, who contributed two Master levels, later became the lead designer at id Software
- Dario Casali, author of a quarter of Final Doom, was hired by Valve Software to work on Half-Life
- Sverre Kvernmo, designer of five Master levels and member of TeamTNT, was hired by Ion Storm for Daikatana
- Iikka Keränen, author of several Doom WADs and later Quake mods, was hired by Ion Storm to create levels for Anachronox and Daikatana, and by Looking Glass Studios to create levels for Thief 2. Keränen was later hired by Valve Software
- John Anderson (level designer), also known as "Dr. Sleep", author of five Master levels and E4M7 of The Ultimate Doom, later worked on Blood, Unreal and Daikatana
- Matthias Worch (level designer) joined Ritual Entertainment to work on SiN. He later contributed to the Unreal series.
Source port era 
Around 1997, interest in Doom WADs began to decline, as attention was drawn to newer games with more advanced technology and yet more customizable design, including id's own Quake.
In late 1997, id Software released the source code to the Doom engine (initially under a restrictive license; it was however released again under the terms of the GNU General Public License). With the source code available, it became possible for programmers to modify any aspect of the game, remove technical limitations and bugs, and add entirely new features.
These engine modifications, or Doom source ports, have since become the target for much of the WAD editing activity (although some purists prefer the original, unmodified engine). As of 2013, several source ports are still actively developed, and Doom retains a following of people who still create WADs.
Types of WADs 
Levels and level packs 
The most common kind of WAD consists of a single level, usually retaining theme of the original game, but possibly including new music and some modified graphics to define a more distinctive setting or mood. Both single-player and deathmatch multiplayer levels are common.
Also common are WADs which contain several levels, sometimes in the form of an episode, replacing some 8-10 levels, and sometimes in the form of a megawad, which replaces all or most levels in the game (36 in Doom, 32 in Doom II).
Megawads often represent the work of several people over several months and in some cases years.
Total conversions 
A WAD that gives the game a general overhaul to incorporate an entirely different game setting, character set and story, instead of simply providing new levels or graphic changes, is called a total conversion. The phrase was coined by Justin Fisher, as part of the title of his Aliens TC, or Aliens Total Conversion. Add-ons that provide extensive changes to a similar degree but retain distinctive parts or characteristics of the original games, such as characters or weapons, are often by extension called partial conversions.
Notable WADs 
The following is a non-inclusive listing of highly popular, unique or historically significant WADs that may be considered uncontroversial in its selection. See the external links section below for alternative lists and review sites.
- 10 Sectors started as a competition at Doomworld, where entrants were challenged to make the best level they could for the BOOM source port using only 10 sectors, with the winner, Michal Mesko, receiving a Voodoo 5 5500 AGP graphics card.
- Doom The Way id Did is a 27-level megawad for Doom originally proposed by Jason "Hellbent" Root and realized as a Doomworld collaboration project. The purpose of the wad was to create three episodes of Doom levels looked and felt as though they could have been in the original game, but without any homages to it. A sequel, Doom II The Way id Did, is currently in development.
- Eternal Doom is a set of levels for Doom II created by TeamTNT after Final Doom, released non-commercially in several versions—the final one on 14 November 1997. Eternal Doom places the player and the original Doom's demons in 32 levels varyingly in the theme of medieval castles and futuristic high-tech bases, featuring a time travel sub-plot. A distinguishing aspect of Eternal Doom is the size of the levels, the average being about four times the size of the levels in Doom and Doom II. Eternal Doom has been praised for the levels' grand architecture and complex layouts, but the size of some of the largest castles, combined with level design which sometimes forces the player to travel back and forth between switches located around the map—often difficult to find, has also been subject to criticism.
- Hell Revealed (May 1997) is a 32-level megawad for Doom II created by Yonatan Donner, one of the players behind the Doom Done Quick speedrunning project, and Haggay Niv. It was designed with the intent of providing a challenge for expert players, and has become infamous for its difficulty: the hardest levels in the set feature battlegrounds where the player is pitted against dozens of the hardest monsters at once, some levels containing around 500 monsters in total. Second to the original games Doom and Doom II, Hell Revealed has been subject to the most Doom speedrunning competition of any Doom WAD. A sequel built around the same concept and featuring yet more monsters, Hell Revealed 2, was created by a different team and released December 31, 2003.
Total conversions 
- Action Doom 2: Urban Brawl is an indie game developed on the ZDoom source port, featuring cel-shaded graphics.
- Aliens TC (1994) by Justin Fisher, based on the movie Aliens, was the first total conversion and is one of the most famous: in the week following the release of Doom II: Hell on Earth, there was more discussion in the Doom newsgroups related to Aliens TC than Doom II. The popularity of the Aliens TC even reached outside the Doom community, for instance providing inspiration for the 1998 Dreamworks game Jurassic Park: Trespasser. Fisher was offered employment by various game developers (including Dreamworks for the team that would later make Trespasser), but declined in order to finish his university degree. Aliens TC was noted for its suspenseful atmosphere. The first level is devoid of enemies, a surprising feature considering the fast-paced action of Doom. Later on, however, the player faces the aliens and even gets to use the powerloader from Aliens as a weapon. Fisher had gotten the idea to create the Aliens TC within his first five minutes of playing Doom in late December 1993, noting a similarity in atmosphere of Doom and the movie. Incidentally, it has later become known that id Software originally planned to base Doom on an Aliens license, but abandoned the idea in the early stages of development.
- Batman Doom uses characters and locations from the world of the comic book superhero Batman.
- Chex Quest - A total conversion made so DOOM can be approved for children. This was packaged in Chex cereal boxes, however when the promotion ended fans put Chex Quest up for download on the Internet.
- Doom 64 TC is a replication of Doom 64, the Nintendo 64 version of Doom, which contains different levels, graphics and sounds.
- Goldeneye Doom2 is a modification of Doom II that adds elements from the Nintendo 64 game GoldenEye 007.
- HacX was originally released as a standalone commercial game, but eventually released as freeware. HacX includes all-new content and the game behavior has been extensively modified to account for its unique cybernetic science fiction setting.
- Paranoid is an 8-level modification of Doom II (using the GZDooM engine) that is intended to be a faithful recreation of Half-Life. It features new weapons, enemies, graphics, sounds, models, skies, 3D architecture, a hub structure, a story-driven mission, and much more.
- Sonic Robo Blast 2 is a modification of the Doom engine, that turns it from a first-person shooter into a third-person platformer based on Sonic the Hedgehog.
- The Darkest Hour is a 7-level modification of Doom 2 that puts the player in the Star Wars universe. It was followed by a 5-level "prequel" called Dawn: A Prelude.
- Void is a single-level modification based on American McGee's Alice.
- Doomsday of UAC (also known as UAC_DEAD after the file name) by Leo Martin Lim, released June 23, 1994, featured what was considered one of the most realistic environments of the time. Exploiting an until-then unknown bug in the Doom engine's rendering code, it also introduced a special effect in the form of an "invisible stairway"; this trick has been used extensively later on.
- D!Zone by WizardWorks Software, an expansion pack featuring hundreds of levels for Doom and Doom II. D!Zone was reviewed in 1995 in Dragon #217 by Jay & Dee in the "Eye of the Monitor" column. Jay gave the pack 1 out of 5 stars, while Dee gave the pack 1½ stars.
- Freedoom is a project to create a free replacement (modified BSD License) for the set of graphics, sound effects, music and levels (and miscellaneous other resources) used by Doom. Since the Doom engine is free software, it can be distributed along with the new resources, in effect providing a full game that is free. Freedoom would also allow users to play any of the thousands of other WADs that normally require the original game. Despite its name, Freedoom resources require an executable with support for additional features introduced by the Doom source port Boom and will not work correctly with an executable build from the original source code release of the Doom engine. The WAD, alongside PrBoom, is packaged in the Fedora RPM software repository. A similar project, Blasphemer, aims to create a complete free version of Heretic.
- The Harris levels - Levels created by Eric Harris, one of the two perpetrators of the Columbine High School massacre. These levels are: Deathmatching in bricks (bricks.wad), Hockey.wad (hockey.wad), KILLER (killer.wad), Mortal Kombat Doom (fightme.wad), Outdoors (outdoors.wad), Station (station.wad), and U.A.C. Labs (uaclabs.wad). Dylan Klebold, a friend of Eric Harris and the other perpetrator of the massacre, was credited for playtesting the Deathmatching in bricks map.
- The Sky May Be - A notable joke WAD and the "Strangest WAD ever made", most of the game takes place in an over sized sector, where many textures are replaced with solid colors, and many sounds replaced with audio from British television programs. The WAD was mentioned in Doomworld's The Top 10 Infamous WADs list.
Many level editors are available for Doom. The original Doom Editing Utility has been ported to a number of operating systems, but lost significance over time; however, many of today's editors still have their roots in DEU and its editing paradigm, including DETH, DeePsea, Linux Doom Editor, and Yadex. Other level editors include WadAuthor and the relatively young Doom Builder (initially released in summer 2003), which, among other things, features a 3D editing mode.
A number of other, specialized editors also were created over time to modify graphics and sound lumps, most notably SLumpEd, Wintex, XWE, and SLADE. Things, such as monsters and items, and weapon behavior can also be modified to some degree using the executable patching utility DeHackEd. In ZDoom, modders can develop new monsters, weapons, and items through a scripting language called DECORATE, made to address many of the shortcomings of DeHackEd - such as not being able to add new objects, and not being able to deviate very far from the behavior of the original monsters and weapons.
The utility Slige can be used to automatically generate random maps. Slige has a cumbersome approach when creating levels and therefore a newer tool called Oblige has been created. This tool is entirely coded in Lua.
WAD2 and WAD3 
In Quake the WAD files were replaced with PAK files. WAD files still remain in Quake files, but their use is limited to textures. WAD2 and WAD3 use slightly larger directory structure, so they're incompatible with Doom.
- Joseph Bell, David Skrede: The Doom Construction Kit: Mastering and Modifying Doom, Waite Group Press (April 1, 1995), ISBN 1-57169-003-4
- Hank Leukart: The Doom Hacker's Guide, Mis Press (March 1, 1995), ISBN 1-55828-428-1
- Steve Benner, et al.: 3D Game Alchemy for Doom, Doom II, Heretic and Hexen, SAMS Publishing (1996), ISBN 0-672-30935-1
- Kushner, David: Masters of Doom: How Two Guys Created an Empire and Transformed Pop Culture, Random House Publishing Group 2003, ISBN 0-375-50524-5; pages 166–169
- Larsen, Henrik: The Unofficial Master Levels for Doom II FAQ, version 1.02 (retrieved October 4, 2004)
- "5 Years of Doom". Doomworld.
- Yadex's Homepage
- "John Carmack Answers". Slashdot. Retrieved 04-13-07.
- Green, Shawn & McGee, American (1994). "Doom Conference". Planet Rome.ro. Retrieved May 7, 2008.
- John "Dr. Sleep" Anderson article at the Doom Wiki 05-07-08
- Fisher, Justin (1998). "5 Years of Doom interview at Doomworld". Doomworld.com. Retrieved May 7, 2008.
- TC Aliens TC article at the Doom Wiki
- Doomworld - The Top 100 WADs Of All Time: 1994
- Jay & Dee (May 1995). "Eye of the Monitor". Dragon (217): 65–74.
- "Freedoom :: Download". Freedoom project website. Retrieved 2008-10-29.
- Blasphemer homepage
- Doomworld: The Top 100 WADs Of All Time (retrieved December 6, 2004)
- 1999 Slashdot interview with John Carmack (retrieved December 9, 2004)
- Interview with Justin Fisher (retrieved December 9, 2004)
- idgames archive - hosted by gamers.org and maintained by longstanding community members Frans P. de Vries and Ty Halderman.
- Doomworld's web-based front-end to the idgames archive - includes search and rating systems
- World's first original WAD created by Jeff Bird.
- Modifications and add-ons for the Doom series at the Open Directory Project
- WAD format article at the Doom Wiki
- IWAD article at the Doom Wiki
- PWAD article at the Doom Wiki