Amazingly, the PS1 version of Ultima Underworld is populated by non-sprite 3D portions.

“The biggest difference to the environment is that all the sprite models of the original game have been replaced by all-new 3D ones. Some of the original UW sprites were pretty appalling (e.g. the bat that looked to be about a dozen pixels) but these were much improved in the sequel. Time hasn’t been entirely kind to most 3D modelling of the mid 90’s and these new models do look basic and cartoonish. They don’t move around the world smoothly either and give the impression of being pre-rendered in which case I’d far rather they had skipped the 3D modelling part and just redrawn everything the old-fashioned way. Most of them don’t look too bad – the giant rats are kind of cute, looking more like giant mice. The rotworm is possibly the worst and looks more like something left behind by one of the giant rats.”

Source: Ultima Underworld – PS1

via: Ultima Codex