This fixes Green Hill Zone's collision errors in the recently discovered early prototype of Sonic the Hedgehog 2. You must select Green Hill Zone from the level select menu (code below). This hack also enables Tails in Emerald Hill Zone.
Level Select Code:
Up, Down, Down, Down, Down, Up, A+Start
Minor problems with this patch:
Patch this to a copy of
Sonic The Hedgehog 2 (Early prototype) (dumped by hidden-palace.org).bin.
Sonic_The_Hedgehog_2_(Early_prototype)_(dumped_by_hidden-palace.org).bin
CRC32: 39FAAA70
MD5: A460BF633579A80EEBBC09D6809E1B09
SHA-1: 5B51B4D98CB4A7A38157DC4AB9462164DD224BFD