As a kid I played Ken's Labyrinth, a raycaster FPS from around the same time as Wolf3D. Only years later I found out that this was actually the same Ken Silverman that went on to create the Build engine for Duke Nukem 3D etc. Kind of funny considering the vast difference in tone between these two games.
edit:
https://en.wikipedia.org/wiki/Ken%27s_Labyrinth