Sega's Japanese website lists a special version of the original Sonic the Hedgehog designed for the Nintendo 3DS. The old game sports some new features, according to CVG, but has not yet been confirmed for the West.
Sonic originally released on Sega Genesis and has made its way to other platforms over the years. 3D Sonic the Hedgehog adapts the experience especially for the 3DS. It enables Sonic to perform the spin-dash move, which first came about in Sonic the Hedgehog 2, and supports a save-anytime function and an option to play in stereoscopic 3D or classic mode. The latter curves the screen so it resembles an older TV.
Players can also enjoy the convenience of a stage select and adjust the sound for a retro flair. 3D Sonic contains both the Japanese and English versions.
Via: Classic Sonic the Hedgehog breaking into 3D with eShop release