The Dark Mod is a free and open-source software first-person stealth video game, inspired by the Thief series by Looking Glass Studios. The game provides the basic framework and tools for more than 170 fan-made missions, including several multi-mission campaigns. The Dark Mod was founded by David Massey and first released in 2009 as a total conversion mod for Doom 3. Version 2.0 was released in October 2013 as a standalone game using the open-source id Tech 4 game engine.