"nGlide is a 3Dfx Voodoo Glide wrapper. It 'emulates' 3Dfx Glide Library, so you don't need a 3Dfx Voodoo graphics card to play 3Dfx Glide API games. nGlide translates all Glide callings to Direct3D. Glide wrapper also supports high resolution modes."
... for Glide based games like "Gradius 4"
I tried on a PC game here that only supports Glide, and it worked without a single problem.