I remember a fully 3d game from quite a bit earlier than then! Spectre for Macintosh, from 1991: https://en.wikipedia.org/wiki/Spectre_(1991_video_game) , and some gameplay at https://www.youtube.com/watch?v=r-F3XISR3ME
I mean wizardry was technically a 3d game if you just consider the way they show the geometry of the dungeon. Stuff like bards tale and some of the ultimas took that and ran with it.