I was brousing around the internet for Sonic 2 stuff and came across a hack of sonic 2. I downloaded it and played it and wow Hidden Palace,Wood Zone,Genonyde City and Dust Hill Finished in this guys vision of the levels and best yet even one with knuckles in it. So what it is is the Original Sonic 2 with Beta Levels as well. Enjoy:
http://www.shadowsoft-games.com/s2long/
BTW you need Gens to play it: http://gens.consolemul.com/downloads.shtml