When you're using the 3Dfx renderer, you will need the appropriate Glide library for your 3Dfx card.
Pick a folder from the table below and copy glide3x.dxe from it to the game folder (next to the EXE).
| Card | Folder |
|---|---|
| Voodoo | v1 |
| Voodoo II | v2 |
| Voodoo 3, Banshee | v3 |
| Voodoo 4, 5 | v4 |
| Voodoo Rush | vr |
These have been copied from the DOjs repository.