Bubsy 3D (lost build of unreleased SEGA Saturn port of 3D platformer; 1996-1997)
From The Lost Media Wiki
Bubsy 3D is a 1996 PlayStation video game that is often considered one of the worst video games ever made. It is the last title - and only 3D one - in the Bubsy series.
A Sega Saturn version was also in development, originally meant to come out in Winter 1996, but was delayed to Spring of 1997.
This version ended up cancelled when the game was a critical and commercial failure. The Sega Saturn version was going to based on the original 32X development models.
No prototypes of the Sega Saturn version have resurfaced.
References
http://segaretro.org/Bubsy_3D Sega Retro article.