Sonic the Hedgehog (1991 video game)

Sonic the Hedgehog is a 1991 platform game developed and published by Sega for the Sega Genesis. It was released in PAL regions on June 21, North America two days later on June 23 and in Japan the following month. The player controls Sonic, a hedgehog who can run at supersonic speeds. The story follows Sonic as he aims to foil the mad scientist Doctor Eggman's plans to seek the powerful Chaos Emeralds. The gameplay involves collecting rings as a form of health, and a simple control scheme, with jumping and attacking controlled by a single button.

Development began in 1990 when Sega ordered its developers to create a game featuring a mascot for the company. The developers chose a blue hedgehog designed by Naoto Ohshima after he won an internal character design contest, and named themselves Sonic Team to match their character. It uses a novel technique that allows Sonic's sprite to roll along curved scenery which was based on a concept by Oshima from 1989. Sonic the Hedgehog, designed for fast gameplay, was influenced by games by the Mario creator, Shigeru Miyamoto. The music was composed by Masato Nakamura, bassist of the J-pop band Dreams Come True.

Sonic the Hedgehog received positive reviews for its visuals, audio and gameplay and is widely considered one of the greatest video games. It sold over 40 million copies across all platforms, becoming one of the best-selling video games. On the Genesis, which it was bundled with, it sold over 15 million copies, making it the best-selling Genesis game. It established the Genesis as a key player in the 16-bit era and made it competitive with the Super NES. It has been ported to multiple systems and inspired several clones, a successful franchise, and adaptations into other media. Sonic the Hedgehog 2 was released in November 1992.