I remember seeing this really old 20 second trailer
https://www.youtube.com/watch?v=JFkubVLD3iA
Apparently the Barbarian was originally supposed to wield axes and I do have a faint memory of actually seeing somewhere the Barbarian wielding two of them at the same time. Amazon can also be seen wielding a sword, which suggests that the original plan was to have her fight with one-handed weapons.
Other things of note:
- Some places look very familiar, might be possible some of the levels from late 90s made their way to the 2000 release in unchanged form
- Final game rarely if ever uses textures above 256x256 resolution. It seems like that's because they are simply reusing the ones from early development that are a relic of the old technical limitations.
- The water effect remains exactly the same
- No shadows on dynamic objects - the lightning system was changed drastically in full release to cast shadows not only from level geometry, but characters and objects found throughout levels as well
- Animations and movement system are vastly different - no motion capture it seems
- Some models remain unchanged - note the lamp for example
- The physics system was already in place
It's interesting to see that quite a lot of stuff was retained, considering the prolonged and continually delayed development of the game.
Overall, had the game been released in the 90s, it's possible it would have played a lot more like Heretic II.