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 other uses in various games, such as entering Special Stages in "Sonic the Hedgehog 2", and leveling up in "Sonic Heroes". In the 2D games, checkpoints take the appearance of posts, while in 3D games they are either small gates or pads on the ground. Springs are a staple in the "Sonic" series. They are scattered throughout the levels and serve to catapult the player at high speeds in a particular direction. Sometimes they allow the player to proceed further in the level, while other times they are used to hinder the player, usually by sending Sonic towards a dangerous