Blue Sphere

Blue Sphere is the game created by locking on Sonic & Knuckles to Sonic the Hedgehog. It is a compilation of 140 million "Special Stages" in the same style (and engine) of the ones featured in Sonic the Hedgehog 3 and Sonic & Knuckles. After compleating all 140 million stages, it repeats from the beginning.

Blue Sphere can also be created by locking on Sonic & Knuckles to any other Genesis game, producing one of the stages featured in the Sonic the Hedgehog Blue Sphere, based on something in the header of the game.

The name Blue Sphere comes from the name it is called in Sonic Mega Collection.