Would it be possible to just darken the game world (avoiding the UI) by using the necessary D3D9 methods?
http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx
Edit, bah, nm, this affects the entire screen too. Hmm.
Edit 2 - I think the only way to affect ONLY the game world might be to run its RGB values through a simple macro that reduces them by whatever amount makes sense for the char/equip/place. Probably the lights' RGBs, but I suppose vertex RGBs would work too. /shrug