Sonic 3 & Knuckles is a platform video game released for the Sega Genesis, created by locking Sonic the Hedgehog 3 with Sonic & Knuckles through unique lock-on technology. This combined game encompasses all zones from both titles and introduces exclusive features. Initially intended as a single release, development was split due to time constraints imposed by Sega.
Sonic the Hedgehog 3 & Knuckles (or simply Sonic 3 & Knuckles or Sonic 3 Complete Edition) is a platform video game which is the result of locking-on Sonic & Knuckles with Sonic the Hedgehog 3 using the former catridge's unique "lock-on" technology. It is essentially a large combined game of its two lock-on components and contains all Zones from the said games and also contains special features unique to this game. This would have been the original Sonic the Hedgehog 3 the developers intended but time constraints by Sega resulted in the game being split into two.