Sonic & Knuckles

Sonic & Knuckles is a game released to the Sega Genesis starring [{Sonic the Hedgehog]] and Knuckles the Echidna. It is the first game to feature Knuckles as a playable character. Its success led to Knuckles becoming a playable character in Sonic the Hedgehog 3. It has since been ported to the GameCube, DS, and Virtual Console.