Legend in the Sonic research community drx has managed to get his hands on 5 new Sonic game prototypes including a Sonic CD beta.

List of games are -
* Sonic CD - Prototype 806
* Sonic Adventure 1 (E3 Trial)
* Sonic Adventure 1 LE (dumped from a GD-R)
* Sonic Adventure 2 (Mar 18, 2001 prototype)
* Sonic Adventure 2 (Nov 28, 2000 preview prototype)

So far a member at Sonic Retro has discovered there is a level select in the Sonic CD beta that has Collision Chaos missing from the levels. Expect more developments soon.

Sonic Retro topic

drx’s Hidden Palace site