There are a bunch of games that run 3Dfx hardware that are essentially PC based and emulated in MAME. The purpose of the MAME project (as we all know) is to preserve the games, so everything will always be emulated in software, playability be damned.
If these were going to be emulated and playable, you'd need a stand alone emulator that supports 3D acceleration, like ElSemis Model 2 Emu. Unfortunately, I believe that Incredible Technologies has politely asked that these games NOT be emulated.