Doom (or Doom 2 which had basically the same engine with just bugfixes and support for Doom 2 entities) didn't actually need an FPU. Even 386DX's or 486SX's had no FPU so no games from the pre-1995 era really depended on it.

I remember Falcon 3.0 and perhaps some other simulation games having support for FPU for those few who had one however...