As an addendum to the above notes about
Interplay's Descent, it featured full 3-D graphics two full years before Quake hit the market. It did not make use of the
FPU, since most computers simply didn't have a
FPU.
Since it did not have the assistance of a FPU, the Descent engine made heavy use of fixed-point arithmetic for non-integer calculations. This method is reasonably fast, and I remember actually getting decent framerate running Descent on the diskless 33MHz i486 workstations in the basement of the public library I was working at in 1994. I later acquired a 100MHz i486 system, and was able to run the game in full 640x480 splendour and still get magnificent framerates. (There were no 3-D accelerators at the time, so this was really quite a feat.)
Descent made full use of texture mapping and Gouraud shading to create what was, in those days, considered to be an excellent gaming environment. You could fire a missile down a narrow hallway, and watch the glow from its tailpipe light up the walls around it as it flew by. The 6DOF (Six Degrees Of Freedom) aspect made it especially fun; everything was done in zero-G and you could rotate your ship in any direction you wished.
The only really sucky thing about it was that you had no Guide-Bot in Descent 1 to show you where to go, and some particularly maze-like levels could get really lame after wandering around in them for an hour, not knowing quite how to proceed to the next section. (The Guide-Bot showed up in Descent 2.)