Sonic and Knuckles
Sonic and Knuckles pushed the boundaries of what was possible with console technology at the time with its “Lock-on technology”. This allowed for connecting it with Sonic 3 and even Sonic the Hedgehog 2 to unlock new features for both games. While the latter allowed for playing as Knuckles in Sonic 2, Sonic 3 became Sonic 3 and Knuckles. Level layouts were slightly changed and Knuckles was playable throughout the entirety of Sonic 3’s levels.
The Super Emeralds could also be earned, allowing Sonic, Tails and Knuckles to transform into their respective Hyper and Super forms. This was also incredible at the time but Sonic and Knuckles was still its own game, presenting two different stories and a tougher difficulty in addition to everything that made Sonic 3 so great.
