If I had a nickel for every time a Sonic prototype was found on a sketchy Chinese website I’d have two nickels. Which isn’t a lot, but it’s still weird that it happened twice.
I love this prototype because half of the sound design is completely different in addition to the audio mixing being totally messed up. It's fascinating how so much of the later development of the game seemingly went specifically into fixing the sound.
It was dumped by PREMIERE sometime in 1993 and distributed over BBS before the game was released, as the ROM contains data for a scene intro by the group. Since its release, the ROM continued to be distributed by the Chinese through ROM sites and bootleg CDs, cartridges, and Super Magic Drive floppies. It was eventually rediscovered and made available by Elliotro on August 1, 2000, allowing it to be properly identified and archived.
Sonic 3 wasn't going to be ready for release by Christmas so they had another development team rush this out to have something on shelves that Christmas.