There are gamers who love old school action first person shooters, and there are gamers who enjoy stealth based FPS's (first person skulkers). The new Dark Mode for Doom 3 appeases to the rare gamer who wants to play Thief inside his Doom.

While the source code to id Software's Doom 3 was already primed for release it was the lawyers that kept it from going forth on the Internet, but now the ambulance chasers are satisfied.

John Carmack twittered that it's finally in the hands of aspiring developers who want it. Apparently some of the code was rewritten because it made the legal suits nervous. Github has it.