Holy thread resurrection, Batman!
SuperCow said:- The Duke Nukem engine was an important evolution just for the fact that you could do the spiralling staircase case (i.e. you could be at two different height levels for the same XY position), among with other features.
Dark Forces engine could do that as well and was released almost a year before it.
Quake 1: First attempt at 3D with polygons and texture mapping w/ widespread perspective correction, although limited to every 16th pixel with interpolation for those in-between; initially a software rendering approach.
That's nothing. IIRC the Descent engine allowed to different "rooms" to occupy the same XYZ coordinate space yet be logically distinct!
Not strictly true. Whilst it was like this on a default installation, there was a console setting that could be made to change this to every pixel if desired.
dont forget strike commander first game to use gouraud shading
shattered steel first game to combine voel terrain with polygon models