I don't know how many of you have noticed this yet. As their website puts it "THE DARK MOD is a total conversion for Doom 3, turning it into a dark and moody stealth game inspired by the Thief series by Looking Glass Studios. We have created a toolset with revamped gameplay, AI, graphics, HUD and weapons to allow fans to create missions in a gothic steampunk universe." The mod should work on Linux. Never tried it yet. I was wondering if someone could run some extensive test to see how it works with linux graphics, both Nvidia and ATI. TDM may be the most advanced game that works on Linux to this date.

You should try it yourselves.
Screencast from an upcoming Fan Mission (just to make an idea what this mod is capable of): http://www.youtube.com/watch?v=9EEEi-Hiu-I