Behold! The Nick Arcade Build of Sonic 2. This is a very early prototype based on sonic 1. here are some screenshots:
And... a very glitchy green hill zone:
it's impossible to complete the first level so i have also included the level select code enjoy:
http://www.megaupload.com/?d=DZLB85S0
Note: I do not own this rom. i have just put into a .rar file along with level select.
For proof, here is the original link:
http://www.hidden-palace.org/?releases/34