UPDATE:There is a new version of the game, visit the official site.
THE DARK MOD 2.0 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.
Visit the official site for newer versions, and for Linux-Mac versions, also at the official site you can find a lot of maps and campaigns.
Note: Install the game in the folder darkmod
The Dark Mod 2.0 (windows)
2.0 GiB - 3,081 downloads
The Dark Mod 2.0 (Source Code)
23.4 MiB - 349 downloads