From Sonic Retro
Alongside the production of Sonic X-treme, STI was working on another game only known as Sonic Saturn. Rather than use sprites for sonic, though, it was going to use a 3D model for Sonic. It was never actually announced publicly that it was in production, but didn't get very far before being cancelled. The bonus rounds were going to be a game of pool.
|Unreleased Sonic the Hedgehog Games|
Sonic's Edusoft (Master System)
Sonic Sports (Sega 32X)