Nice! I think this is definitely an improvement over the current ATCS.
I don't know if it's possible, but I think it would be awesome if the fog was moving. If it was swirling around a bit with little whisps coming off. It doesn't do that already, does it? :d
This could be partially simulated with an animated shader on or below the surface of the fog volume. Whisps can be done using particles, though it'll need to be slow and subtle to avoid spoiling it IMO.
I like it. The fog's perfect, though as stated I'm not sure how it got there. Make a ruptured pipe or something?
Well, the skirting around the base of the walls look like grilles of sorts - perhaps the fog seeped through them. A leaking pipe could be a nice touch but in the centre of the corridor where the bases are well out of view, so as to avoid crushing framerates.
IF ONLY WE HAD BUMP MAPS....MY i7 CAN DO A LOT MORE THAN RUN THIS GAME.......
Indeed it can. However, sadly, it is unable to detect misuse of the caps lock key.
Anyway, please feel free to make those bump maps and the appropriate modifications to the engine so they can be of use.