The Dark Mod began as a singleplayer total conversion mod for Doom 3 inspired by the Thief series, and is now an entirely standalone freeware stealth game. The Dark Mod is under constant development and improvement by Broken Glass Studios, an independent team of developers.
The Mod actually consists of two separate projects. The main branch of the project consists of the standalone total conversion, while the second branch of the project is the editing application, "Dark Radiant", a completely rewritten version of the open source GTK Radiant editor. Primarily a toolkit for building Thief-like missions, the mod features architecture, stylistics and equipment reminiscent of the Thief series, and modifications and additions to Doom 3's SDK and scripting to improve the physics, modeling, and make enemy AI work similar to Thief AI. The Dark Mod is currently available on Windows, Linux and OS X.
Though TDM is inspired by the Thief series, it has its own separate setting and stories to avoid any copyright and legal issues. Broken Glass Studios is a team of hobbyist independent developers who develop TDM on an open-source basis, many of them Thief fans. It is also worth noting that new contributors to the project also include people who originally didn't have a long-term participation in the Thief fandom and discovered the game while in search for a quality open-source stealth game.
Two alpha demonstrations, Thief's Den and The Tears of Saint Lucia, were released to demonstrate how the Mod was meeting its goals. The first proper beta version, 1.0, was released in October 17th, 2009. Update v1.01 was released on March 12th 2010, and v1.02 was released on May 25th 2010.
27th Nov 2011: Version 1.07 was the latest release at that date.
9 Oct 2013: The Dark Mod 2.0 is now completely standalone, which means you no longer need to own Doom3 to play it! We have spent a tremendous amount of time and energy replacing all the sounds, textures, particle effects, and models that we had been using. Hopefully this will open up a whole new audience of people who didn't want to have to purchase a different game in order to try The Dark Mod.
26 December 2013: The Dark Mod is named "Mod of the Year" by PC Gamer magazine. And we quote: "It's a tremendous achievement - a detailed tribute to the Thief series."
29 January 2014: Version 2.01 released.
7 July 2014: Version 2.02 released.
13 July 2016: The release of version 2.04.
15 February 2017: The Dark Mod reaches version 2.05 and arrives to Steam as a freeware offering, after a highly successful Steam Greenlight campaign that broke records and exceeded expectations.
27 May 2018: The Dark Mod releases version 2.06, which now has a 64-bit build, Multi-Core support, EFX Audio, Uncapped FPS, Scrolling Mission Install and Download Lists, FFMPEG video, and Experimental "Soft Shadows". It has been optimized for modern OpenGL and should offer a substantial performance increase for modern players.
1 July 2020: The Dark Mod releases version 2.08, with improved visuals, performance, AI, gameplay and many new assets.
15 february 2021: The Dark Mod releases version 2.09, which comes with many performance, graphics/shadows/textures improvements, new NPC AIs and assets, and some gameplay improvements.
The community has produced a total of 155 missions to date (as of April 2021), in varied settings, environments and with varied narratives, objectives and gameplay approaches.
Over time, many updates to the interface have been made, including in-game mission downloading, massive AI improvements, new animations, vocal sets and more.
The map editor, Dark Radiant, has also had a ton of improvements, but the most noticeable ones are the ability to create readable texts and pages directly in the editor via a GUI, and also the GUIs for the conversation editor and the stim/response editor.
Some video tutorials for the editor can be viewed in this category.