>>11858168
>Duke 3D was mostly pre-renders
To a very large part, yes they were, Duke Nukem 3D made VERY extensive use out of 3D models which were crafted by Chuck Jones (who would later do much of the monster and character design in Half-Life and Half-Life 2, among other Valve games).

For exceptions, Duke's hands and his kick are digitized, and his shotgun is a Winchester 1300 Defender with a factory pistolgrip, which George Broussard bought used, having previously been owned by the Texas Department Of Corrections.
He figured it would be cool to put a real shotgun in the game, and he was right, but people and journos complained in previews that it looked dull and like "a gray banana," so he bought a Tac-Star vertical front grip and vented heat shield to put on it, to make it look more distinct, and I'd say that did the trick.
To me, Duke's shotgun is iconic, drawing the radiation tre-foil logo on it for Duke is a neat and fun touch.

The explosion and fire graphics in Duke Nukem 3D were mostly sourced from Pyromania FX, which is a royalty free stock asset set you buy once and then you're free to use the contents in all of your productions. You can see a lot of the same assets used independently in various other games of that time.