Freedoom

About

Freedoom targets compatibility with Doom, id Software's original first-person shooter, and its vast catalog of fan-made levels and mods spanning over three decades. Freedoom is a complete, free replacement for Doom's game content — levels, artwork, sound effects, and music — released as three separate 'games': Phase 1 (36 levels across 4 episodes, aiming for Doom/Ultimate Doom mod compatibility), Phase 2 (32 levels aiming for Doom II mod compatibility, adding extra monsters and a double-barrelled shotgun), and FreeDM (a 32-level deathmatch-only set). It is not itself a game engine — it must be paired with a separate Doom source port such as GZDoom to actually run.

How it differs from the original

Unlike a straight Doom clone, Freedoom explicitly avoids reusing or closely copying Doom's assets, story, or trademarked elements — for example, it substitutes the fictional 'AGM' corporation for Doom's trademarked 'UAC' — and contributors are told the goal is an original game that happens to be compatible with Doom mods, not a copy of Doom's content.

Getting started

Freedoom ships only game data files, so it must be paired with a separate Doom source port, such as the recommended GZDoom. On Windows the data files go alongside the engine executable, while Linux/BSD packages often include ready-to-run launcher commands and desktop menu entries for each of the three games.

Known issues & limitations

• compatibility: All levels must be vanilla-compatible and cannot exceed original Doom engine limits.

Media

Additional notes

Documentation

A full manual with an introductory tutorial and a monster/item reference is available in multiple languages, including a printed edition for purchase.