Mighty the Armadillo (hack)
From Sonic Retro
Mighty the Armadillo is a hack of Sonic the Hedgehog for the Sega Mega Drive/Genesis by Yuski. The hack features Mighty the Armadillo, who appeared in both SegaSonic Arcade and Knuckles' Chaotix. Features include new art, palettes and layout for Green Hill Zone.
Mighty the Armadillo is one of the oldest ROM hacks, with work on it starting in June 2000 with the help of Gen-SMS. It has since been discontinued in order for Yuski to work with Esrael on Sonic Gaiden.