A mod is a change to a game made by someone other than its publisher. It might be a new level, a new set of monsters, different rules, or so much new material that only the engine underneath is left, which is known as a total conversion. The practice is older than the word. Edge pointed out in 2003 that even typing in a few lines of BASIC to get extra lives on the Spectrum was “a mod by any reasonable definition of the term”.
What makes modding surprising is how much of the games industry came out of it. Three of the best-known multiplayer games of the 2000s and 2010s, Team Fortress, Counter-Strike and Dota, began as free modifications of other companies’ games, and all three ended up as Valve products.
Fast facts
- Early example: Castle Smurfenstein (1983), a reworking of the Apple II game Castle Wolfenstein with Smurfs in place of its characters.
- Breakthrough: Doom (1993), whose WAD files let players add levels, graphics and sounds without altering the original game.
- Tools: at first written by players, such as the Doom Editing Utility; later supplied by developers, such as Valve’s Half-Life software development kit.
- Famous mods: Aliens TC (Doom), Team Fortress (Quake), Counter-Strike (Half-Life), Defense of the Ancients (Warcraft III), DayZ (ARMA II).
- Today: official tools such as Bethesda’s Creation Kits and storefronts such as the Steam Workshop.
Before Doom
Players had been making their own content since the early 1980s, usually with tools the publisher supplied. Lode Runner (1983) shipped with an editor for building and saving new screens. Bill Budge’s Pinball Construction Set (1982) let users design tables and share them on disks, and Sensible Software’s Shoot-’Em-Up Construction Kit (1987) let them draw sprites, make sound effects and plan attack waves “all without having to program a line of code”, as Wireframe put it in 2022.
Mods in the stricter sense, altering a game its makers had not opened up, started with Castle Smurfenstein. Wireframe dates it to 1983 and calls it “one of – if not the – earliest mods around”: it took Castle Wolfenstein and replaced its characters and text with Smurfs. Edge saw it as “a typical irreverent start to the phenomenon known as modding”, a pattern of dropping a pop-culture favourite into a popular game that Doom modders would repeat a decade later.
Doom and the WAD
The hobby grew enormously with Doom in December 1993. id Software kept almost all of the game’s data (maps, graphics, sounds and music) in a single archive, DOOM.WAD; the name stood for “Where’s All the Data?”. Fabien Sanglard’s study of the engine explains what made this so easy to extend. A WAD is a header, a series of data blocks called lumps, and a directory at the end giving each lump’s name, size and position. When the game looks up a lump by name, it searches the directory from the end backwards, “intentionally”, Sanglard writes, so that a lump loaded later wins. A player’s own WAD, added on the command line, could replace any map, sound or picture in the original while leaving DOOM.WAD untouched. Only the monsters’ behaviour and the map names were fixed inside the program itself.
id asked for one courtesy. In May 1994, releasing the source of the program that built Doom’s maps, John Carmack wrote: “If you are creating new DOOM maps for other people to use, we would appreciate it if the wadfiles you create use a PWAD identifier at the start of the file instead of the normal IWAD.” IWAD marked id’s own files and PWAD, for the “patch” files as id’s code called them, marked everyone else’s. Edge adds that id also asked that add-ons work only with the registered version of Doom, not the free shareware episode, and that “most modders seemed to stick to this restriction”.
id did not supply a level editor. It explained the file format to a few people in the community, and within a month an “Unofficial DOOM specs” document was online. Players wrote the tools themselves, most famously Raphaël Quinet’s Doom Editing Utility, DEU. Dario Casali told PC Zone in 1998 that he found DEU on a magazine cover disk and “spent the whole night and the next day on the computer, just moving barrels and monsters about”.
By 1995 fan levels were being sold in bulk. Computer Gaming World reviewed WizardWorks’ D!Zone, a $29.95 CD-ROM of 900 new levels for Doom and Doom II with editing utilities for “the sound effects, music, graphics and PWAD files”. id went further in 1996 with Final Doom, which Wireframe describes as “featuring no less than two whole campaigns designed by mod teams”. One of those teams was Dario and Milo Casali. id had contacted them after seeing an eight-level episode they released online. “We were commissioned to build a full 32-level game,” Dario remembered, “and we had under three months to get it done.” They were paid a flat rate for each level.
In December 1997 id released the Doom source code itself “for your non-profit use”, in Carmack’s words, and within about six days, Amiga Format reported, the first ports had reached the Amiga.
Quake and QuakeC
Quake (1996) went further. As well as new maps and graphics, it included QuakeC, a programming language for the game’s rules. PC Gamer explained in 1997 that id had allowed plenty of customisation from the game’s console, and had also “thoughtfully threw in a whole programming language with which the hardcore programmers could do exactly what they wanted”, and listed the results, from Quess (chess played with Quake’s monsters) to Qsoccer and a racing game, QuakeRally. id’s level-design tools were not released at first and “proved cumbersome when they actually did appear”, Edge recalled, so players again built their own, of which Worldcraft “proved the most popular”. From this came the first Quake multiplayer mods, including Capture the Flag and Team Fortress.
Mods that became games
Team Fortress began in Australia, where Robin Walker and John Cook had played a Doom map called Fortress. They made their own version for Quake, released in 1996, which gave each player a class with its own weapons and abilities, from a Field Medic to a Spy. According to Sierra’s InterAction magazine in 1999, it was downloaded 500,000 times. Walker and Cook formed a company to support it, and Valve’s Gabe Newell then “acquired their little company, its technology, and its founders, making them all part of Valve”. Edge saw buying a mod outright as “a sign of things to come”. Valve moved the game to the Half-Life engine; by Christmas 1999 PC Zone was describing Team Fortress Classic for Half-Life as a leading multiplayer game, and Team Fortress 2 later became one of Valve’s most important series.
Counter-Strike was the work of Minh Le, a university student, with Jess Cliffe running the website and recording many of the voices. Le told Retro Gamer that the first version, released in June 1999 for Half-Life, had one mission type, hostage rescue, two character models, about six guns and, he believed, three maps. Players supplied many of the later maps. Le and Cliffe sold the rights to Valve in 2000, and the game left beta that November. Valve encouraged others to follow: by mid-2000 Computer Gaming World reported that the Half-Life software development kit, previously available only under a non-disclosure agreement, was about to be released to anyone, inviting readers to start on “that COUNTERSTRIKE killer you’ve been developing in your head”.
Defense of the Ancients traces back to a custom map for StarCraft, Aeon of Strife, made in 1998. It was rebuilt as a Warcraft III map by a modder called Eul in 2003, extended by Guinsoo (Steve Feak) as DotA Allstars, and refined from 2005 by a developer known as IceFrog. Guinsoo went on to help make League of Legends at Riot Games; IceFrog joined Valve in 2009 to build Dota 2, released in 2013. When Edge visited in 2011, Valve estimated that more than 20 million people played DotA, and its project lead called it “the biggest game in the world that no one has heard of”.
Other mods followed the same route. Desert Combat, a Battlefield 1942 mod, led to its makers, Trauma Studios, being bought by DICE, which closed the studio about a year later. Dean Hall’s DayZ, a zombie-survival mod of ARMA II, had a reported 400,000 players within a few months of its release in 2012, and Wireframe traces the battle royale games that followed partly to mods of DayZ.
A path into the industry
Modding became a way in for individuals too. Dario Casali was flown to Seattle and hired by Valve as a designer on Half-Life. In 1997 PC Gamer printed the testimony of players whose lives Quake had changed, among them Tom Mustaine, a designer at Hipnotic Interactive, who said Quake had let him move from “system administration” into game development. Wireframe followed the same path in 2018 through later examples: the team behind XCOM: The Long War, hired by Firaxis to make downloadable content for XCOM 2, and Nick Pearce, whose Skyrim mod The Forgotten City took 1,700 hours to make, was downloaded 1.8 million times and became a standalone game.
Tools from the developers
By 2003 Edge judged that “user-created content has won its war for acceptance”: a game that failed to release its tools was more worth remarking on in a review than one that did. Developers now shipped editors and kits: Valve’s Half-Life SDK and Worldcraft, and later Bethesda’s Creation Kits for Skyrim and Fallout 4. Releasing tools cost money, and not every game grew a community to use them. Harvey Smith of Ion Storm told Edge that the tools for Deus Ex had been “popular with 500 people. It took a ton of money and time”.
Distribution changed too. Doom’s levels travelled by FTP site, bulletin board and CD-ROM. Today Steam hosts a Workshop for many of the games it sells, so mods can be found through the same storefront as the game. Wireframe noted in 2018 that ModDB was often “the only reliable site” for older mods, “especially those from the Doom/Quake era”.
Sources
- Edge issue 126, August 2003, pp. 60–67: feature on mod culture (“user-created content has won its war for acceptance”; Harvey Smith on Deus Ex’s tools; “Mod crib notes” on Aliens, Capture the Flag, Team Fortress and Desert Combat; history sidebar on Castle Smurfenstein, id’s request about the registered version, and Worldcraft).
- Wireframe issue 3, November 2018, pp. 18–23: “The route less travelled: when modders turn pro” (Castle Smurfenstein in 1983; Final Doom; Aeon of Strife in 1998; Dota 2 in 2013; Counter-Strike; DayZ and battle royale; Trauma Studios; XCOM: The Long War; Nick Pearce; ModDB; Creation Kits; Steam Workshop).
- Wireframe issue 68, November 2022, p. 97: Lode Runner’s editor, Pinball Construction Set, Shoot-’Em-Up Construction Kit, and DEU.
- Fabien Sanglard, Game Engine Black Book: DOOM (2018), section 4.10.1 (WAD format), section 5.8 (lump search order, IWAD and PWAD, the “Unofficial DOOM specs”), appendix E (Carmack’s source release note, December 1997) and appendix F (the doombsp release note, May 1994).
- PC Zone issue 71, Christmas 1998, p. 74: level design feature, interview with Dario Casali (DEU on a cover disk; Final Doom; hired by Valve).
- Computer Gaming World issue 129, April 1995, p. 34: D!Zone (WizardWorks, $29.95, 900 levels).
- Amiga Format issue 108, March 1998, p. 10: news (Doom source released at Christmas; Amiga ports within about six days).
- PC Gamer (UK) issue 46, August 1997, pp. 69–71: Quake feature (QuakeC; Quess, Qsoccer, QuakeRally; Worldcraft; Tom Mustaine).
- InterAction (Sierra), Spring 1999, pp. 48–49: Tom Chick, Team Fortress 2 preview (Walker and Cook, the Fortress map, 1996 release, 500,000 downloads, the acquisition).
- Retro Gamer issue 119, October 2013, pp. 84–87: “The Making of: Counter-Strike”, interview with Minh Le; sidebar “The Mod Squad” (Team Fortress, Defense of the Ancients, Garry’s Mod, DayZ, Black Mesa).
- Computer Gaming World issue 192, July 2000, “Inside Gaming” column: Half-Life SDK to be released to all.
- PC Zone issue 84, Christmas 1999, p. 30: total conversions for Half-Life, Team Fortress Classic and Counter-Strike.
- Edge issue 225, March 2011, pp. 56–57: Dota 2 feature (Eul, Guinsoo, IceFrog, Valve’s 20 million estimate, Erik Johnson).
- Edge issue 244, September 2012: DayZ feature (Dean Hall; 400,000 players).