Blue Sphere
From Sonic Retro
Blue Sphere is the special stage from Sonic 3, also can be accessed if you plug any genesis game (other than Sonic 3 or Sonic 2) into Sonic and Knuckles. It was also an unlockable game in Sonic Mega Collection.
Blue Sphere is the special stage from Sonic 3, also can be accessed if you plug any genesis game (other than Sonic 3 or Sonic 2) into Sonic and Knuckles. It was also an unlockable game in Sonic Mega Collection.