Sonic the Hedgehog platforming of the main levels. The 16-bit "Sonic the Hedgehog " consisted of a giant rotating maze, which many considered a major technical achievement. The most common special stages, however, were segments with the character running through a long tunnel to collect certain items. 3D "collect item" levels, as in "Sonic 3" and "Sonic & Knuckles", used the same perspective but had Sonic collecting all the blue-colored orbs on the surface of a giant sphere. Finally, "Sonic Advance 2" employed a 3D ring-collecting stage, and "Sonic Chaos" ("Sonic and Tails" in Japan) used a variety of gimmicks for its levels.
Sonic the Hedgehog 2 Sonic the Hedgehog 2 Development of the game began in November 1991. The game was developed by both Japanese and American staff at Sega Technical Institute; art director Tim Skelly designed the appearance of the game's new 3D special stages, which were based on an earlier tech demo created by Yuji Naka. The staff increased the speed of "Sonic the Hedgehog 2" in comparison to its predecessor. As with the first installment, the soundtrack was composed by Masato Nakamura. "Sonic the Hedgehog 2" sold over six million copies, making it the second-best-selling Genesis game behind the original "Sonic the Hedgehog".