Freedoom

When the Doom source code was relicensed under the GNU GPL in 1999, it opened the door for an entire ecosystem of source ports and community development. What it did not free was the game’s actual content: the graphics, audio, levels, monsters, and setting that make Doom what it is all remained under id Software’s proprietary copyright. For years, anyone wanting to play the thousands of fan-made WADs and mods required a legal copy of one of the original Doom IWADs as a content base. The Freedoom project was founded to solve that problem.

For readers tracing how the series developed across its major releases, see our Doom games in order guide.

Origins and purpose

Freedoom was envisioned in 2001 by Captain Mellow (Wayne Dean) on the Doomworld forums, with Simon Howard (Fraggle) and Jon Dowland (Teppic) taking charge as the project’s founding technical leads. Simon Howard is also identified as the project’s founder in the Freedoom project’s own 0.12.0 release news. The philosophical parallel drawn on the project’s about page is explicit: just as the GNU project developed a free replacement for Unix, Freedoom aims to do the same for Doom. The result is a collaboratively maintained body of original artwork, music, sound effects, and level design contributed by members of the broader Doom community, all released under the 3-clause BSD license — a permissive open license that requires the relevant copyright, license conditions, and disclaimer notices to be retained. The project is currently maintained by Simon Howard (Fraggle) and Mike Swanson (Chungy).

Three games in one project

Freedoom is not a single monolithic IWAD. It is three distinct game experiences, each targeting a different segment of the Doom mod ecosystem.

• Freedoom: Phase 1. The first part of the single-player campaign, Phase 1 is structured around four episodes containing nine levels apiece, paced to ease players newer to the Doom format into the experience. Its structure mirrors the original Doom and The Ultimate Doom, and it is cross-compatible with mods built for those games. This means that any WAD made for The Ultimate Doom can, in most cases, be loaded over Phase 1 to replace the levels, using Freedoom’s original enemies and artwork as the content base.
• Freedoom: Phase 2. This expands into Doom II territory: a 32-level single episode that introduces additional monster types and the iconic double-barreled shotgun. The levels demand a higher degree of skill than Phase 1. Phase 2 is compatible with the enormous library of Doom II mods, which represents a large share of the custom WAD catalog built up over several decades.
• FreeDM. This is the project’s dedicated deathmatch component. Its arenas contain no monsters and are built specifically for competitive multiplayer in the classic deathmatch format. Like Phase 2, FreeDM is compatible with Doom II mods, though its map design is oriented around player-versus-player combat rather than exploration or puzzle-solving.

Mod compatibility

Because Freedoom functions as a drop-in IWAD replacement, it allows most of the community-created Doom levels and mods described by the project as a decades-long back catalog containing thousands of works to be played without requiring the purchasable commercial IWADs. The move away from Boom as the target engine was announced in December 2015; Freedoom 0.11, released in February 2017, eliminated Boom as the target and aimed toward eventual vanilla Doom compatibility, while initially supporting limit-removing engines.

Freedoom as an asset library

Beyond serving as a playable game, Freedoom explicitly positions its asset library as a reusable creative resource. Freedoom contains hundreds of original textures, sound effects and music tracks that can be reused royalty-free by Doom level authors and other independent game developers. The project’s about page says reuse requires including the same copyright statement and crediting the Freedoom project. Examples listed by the project include Gloomy Dungeons and other standalone games and applications.

Freedoom’s original monster names

Freedoom uses its own names for many of the monsters that replace Doom’s originals. Examples include serpentipede for the imp, trilobite for the cacodemon, assault tripod for the cyberdemon, and necromancer for the arch-vile.

Version history and development milestones

Freedoom has undergone substantial evolution since 2001. Version 0.6.4 (2009) was released partly in response to plagiarized material found in the source tree; earlier releases have since been withdrawn. The project’s current download page provides historical releases only as far back as 0.6.4. Version 0.8, released on January 1, 2014, added BEX message strings and incorporated Double Impact as the fourth episode of Phase 1. Version 0.9, released on October 14, 2014, introduced the modern freedoom1.wad and freedoom2.wad filenames, with Phase 1 targeting The Ultimate Doom and Phase 2 targeting Doom II and Final Doom mods.

The 0.12.0 release in October 2019 introduced a full PDF manual — authored by Simon Howard — and pursued a strong vanilla compatibility focus across its levels. FreeDM received a major overhaul in that release, with weaker levels removed or reworked and Aquatex and Egyptian textures used in some of its levels; Aquatex itself had been introduced in 0.11, which added more than 200 Aquatex textures for mappers.

The most recent major release, 0.13.0, published on January 29, 2024, continued and deepened the vanilla compatibility work. Boom-specific features were removed from the levels, hall-of-mirrors rendering artifacts were greatly reduced, and visplane overflows were fixed. Several entirely new maps were added across Phase 1 and Phase 2 slots. The monster roster saw significant revision: the minigunner was redesigned, and three enemy types were renamed and redesigned — the hatchling (replacing the deadflare), the matribite (replacing the summoner), and the octaminator (replacing the dark soldier). Weapon sprites were broadly improved, and a revised polaric energy weapon was included. Accessibility received attention through colorblind-friendly key indicators, and the manual gained French and Spanish translations.

A separate FD24 development branch was created in August 2024 to provide Freedoom resources corresponding to the ID24 resource set, including a libre replacement for id24res.wad; the work remains separate from the 0.13.0 release.

Development continues actively on the project’s GitHub repository, with automated builds available for those who want to follow in-progress work between official releases.

Licensing and redistribution

The 3-clause BSD license governing Freedoom’s content permits the assets to be reused and redistributed in other projects, provided the required copyright and license notices are retained. This licensing model is also why Freedoom assets can be incorporated into projects with different licensing terms, subject to the license conditions.

The project warns that a number of early Freedoom releases were officially withdrawn after copyright violations were discovered in the source tree.

Recommended engines

Crucially, Freedoom is content, not an engine. It must be paired with a Doom-compatible source port to be played. Of the three officially highlighted options, Crispy Doom is suggested for players who want an experience close to the original Doom look and feel with modern usability improvements. Its parent project, Chocolate Doom, is noted as more faithful to DOS Doom but not recommended for general play due to its replication of unstable original behavior. Eternity Engine is highlighted for players and modders seeking deeper customization and advanced level modification support. GZDoom is positioned as the option for players who want access to the largest range of modern mods, though the download page notes it deviates significantly from original Doom gameplay and cannot play demo recordings compatible with the standard Doom engine.