The Dark Mod is a free, first-person stealth game inspired by the Thief series by Looking Glass Studios. It recreates the essence of the original Thief games on a more modern engine. Both a game and a mission-creation platform, The Dark Mod allows players and mappers alike to enjoy missions in a gothic steampunk universe.

The Dark Mod was officially released on October 17th, 2009. As of October, 2013, TDM 2.0 is now completely standalone, and no longer requires Doom3.