I had an idea for a Doom 3 mod last night.
I had it after i was using the pistol/flashlight mod. I was thinking that a flashlight would be put on all of the weapons, but then all of the lights on the whole base would be turned off because of a major blackout or something. The monitors and some other light sources could still be left on in some cases just for the creepy effect of that being the only light in a room. I think this would make the game a lot scarier and a lot of fun.