http://en.wikipedia.org/wiki/Sonic_%26_Knuckles http://en.wikipedia.org/wiki/Sonic_%26_Knuckles Similar concept, though it's done with an attachment instead of

http://en.wikipedia.org/wiki/Sonic_%26_Knuckles http://en.wikipedia.org/wiki/Sonic_%26_Knuckles Similar concept, though it's done with an attachment instead of linking systems.