Sonic the Hedgehog

Sonic the Hedgehog is a platform game developed by Sonic Team and published by Sega for the Mega Drive/Genesis system. It is the inaugural game in Sega's flagship Sonic the Hedgehog video game series, and was the first title developed by Sonic Team. It was first released on June 23, 1991 in North America, and the next day in Europe. The Japanese Mega Drive version was released on July 26, 1991.

This game propelled the Genesis into mass popularity in North America. After it was released, it eventually replaced Altered Beast as the game bundled with the console, and was later replaced with its first sequel, Sonic the Hedgehog 2. The game featured many novel elements which contributed to its popularity and helped to promote the uptake of 16-bit consoles.

Sonic the Hedgehog added the element of speed to the standard platform formula and introduced other unique elements as well, such as the loops, springboards, high-speed devices, and the rings now permanently associated with the game series.