Here is a Sonic The Hedgehog hack which was entered into a 2007 contest.
Chimpo is a super robot with incredible amnesia due to hardware failure. He (OR IS IT A SHE?!) didn't even know he was a robot to begin with. His exact reasons for destroying all the other robots on the island is unknown other than to fulfil his own enjoyment. Seriously hates frogs.
Features
New layout for levels has been added, along with new sprites for the character, enemies, level background, etc. The title sprite has not been changed however, only the background. ChimpoQ! also has a SpinDash-like attack.
Sonic The Hedgehog (USA_ Europe).md - NOINTRO
CRC32: F9394E97
MD5: 1BC674BE034E43C96B86487AC69D9293
SHA-1: 6DDB7DE1E17E7F6CDB88927BD906352030DAA194
SHA-256: 46160BAA06362C711C9F1A5017CB7371026444936C8AF5E93A78996CF32FF2A6