Sonic n Knuckles

Sonic n Knuckles was the fourth installment in the main Sonic the Hedgehog series and a direct sequel to Sonic the Hedgehog 3. During the development of Sonic 3, it and Sonic n Knuckles were intended to be a single story within the same cartridge. However, due to time constraints and the fact that a large memory capacity cartridge would have been expensive, Sega split the game into two separate installments.