It is unclear what was going through the minds of the executives at Sega when they got the designs for Sonic the Hedgehog but it is clear that gamers loved him. Sonic proved that gamers were tired of slow games and they wanted speed- not just in racing games but in action games too. By the time Sega got to the third Sonic game, the whole speed and nothing but speed was getting a little thin with fans. Sega had to change things up a bit and so they did to great fanfare of fans across the world.
Sega introduced Knuckles in Sonic the Hedgehog 3 and set the whole universe on its head. Knuckles was just what Sonic needed for a foil, even if only for a while. Unlike Robotnik, Knuckles was powerful on the level of Sonic and spry with his actions- not relying on lumbering machinery.
Interestingly, Sonic the Hedgehog 3 was developed alongside Sonic and Knuckles- well, alongside as in they were originally one game. Due to costs in producing one single cartridge that could contain both games, Sega was forced to break up the two and in the process create a new idea that they floundered. Lock-On Technology was introduced with Sonic and Knuckles. Lock-On Technology is similar to how the Game Genie and similar cheat devices work where a game is “locked on” to another game. Coupling Sonic and Knuckles with Sonic the Hedgehog 3 and it is like getting a whole new game- bigger and better than the parts.
It has also been recently proven that Michael Jackson wrote some of the music for Sonic the Hedgehog 3. Seganerds.com has a good dissemination of the information about Michael Jackson’s involvement with the development of Sonic 3.
Sonic 3 has been re-released many times over including Sonic Jam for Sega Saturn (Ebay), Sonic Mega Collection Plus for Playstation 2, Xbox and PC (Ebay), Sonic’s Mega Collection for Xbox 360 and Playstation 3 (Ebay), Sonic Classic Collection for Nintendo DS (Ebay), Sonic and Knuckles Collection for PC (Ebay), Sonic Mega Collection for Gamecube (Ebay) and of course on Steam and Gamersgate.