Another issue I noticed that's prevalent in both opengl and d3d is the game reverting back to 16bit color space after invoking the "Telcom Briefing and Goals" screen (Shift-Tab) and exiting back into game. You can hit F2 and reset it back to 32bit color once you close that screen but it only holds the 32bit setting until that "Telcom" screen is invoked again whether manually, i.e. hitting "Shift-Tab" key in a map - or automatically like at the end of the level. It also reverts back to 16 bit color when you load a saved game. I think it has something to do with the transitioning from those screens that are a hard set resolution of 640X480 independent of the resolution of the game inside the map (like the Telcom screen, load screen, and main game splash screen) and screwing up when the game changes or loads back to the in game map resolution and color setting. I realize the game was basically optimized for 16 bit color space at development due to the hardware at the time but the 32bit setting really does help with some of the color "banding" especially noticeable on sky boxes, lighting transitions on textures, etc. It would be nice not to have to reset it back so often throughout game. If anyone knows of a way to hard set 32bit color - whether as a launch parameter or as a hand-set config tweak I would be greatly appreciative.

I have the same problem. strange thing: you can only change bit depth when are in level.