@Thomas Oddly enough I agree with you.
Maybe I asked the wrong question. Some Warp3D games want the video mode in 15-bits and people do get them to work with voodoo, so how?
Maybe they are promoting the video to 16-bits? like Nightlong
So how do you then promote to 16-bits?
Nightlong can be promoted to 16-bit via Modepro or a similar utility.
Other 15bpp programs don't work if they query the list of available screenmodes and just quit if they don't find a 15bpp mode. Somebody write this program to tell the system that 15bpp modes are available and just point to the same endian 16bpp mode.