Sonic the Hedgehog was released on July 26, 1991 in Japan.
In 1990, Sega ordered its in-house development studio, AM8, to develop a game featuring a mascot for the company. This was a position already held by the character Alex Kidd, but he was considered similar to Mario and deemed unsatisfactory; Sega president Hayao Nakayama wanted a character as iconic as Mickey Mouse. Sega had competition from Nintendo and its mascot, Mario, in mind; Nintendo was dominant at the time, particularly after the release of the successful Super Mario Bros. 3, and Sega wanted a foothold in the industry. Although the company had some success with Genesis ports of its arcade titles, it knew this would not be enough.
AM8 developed ideas for characters, an engine, and gameplay mechanics. Development emphasized speed, so AM8 eliminated character designs not associated with fast animals, as well as fast creatures like kangaroos and squirrels. One idea, a rabbit able to grasp objects with prehensile ears, showed promise at first but was too complex for the available hardware. The team narrowed its search to animals that can roll into a ball, their idea for an attacking move. Designers then realized that this would not seem aggressive enough, so they focused on two animals with spikes: armadillos and hedgehogs. The hedgehog character, first proposed by Naoto Ohshima, prevailed, although the armadillo would later become the basis for Mighty the Armadillo (who first appeared in 1993's SegaSonic the Hedgehog). Ohshima has admitted since that he created Sonic's basic design by combining Felix the Cat's head with Mickey Mouse's body.
Sonic was originally teal-colored, then a light shade of blue, but he was changed to dark blue so he would stand out against certain backgrounds and to match the Sega logo. His shoes were colored red through the inspiration of Michael Jackson's boots on the album cover for Bad and the outfit of Santa Claus, whom Ohshima saw as the most famous character in the world. Sonic's spikes were emphasized to make him look sleeker, and he was given the ability to spin while jumping (so attacking and jumping could be controlled with one button). The new character was originally named Mr. Needlemouse, but the 15-member AM8 changed his name to Sonic and their studios to Sonic Team. Ideas proposed to flesh out the character included placing him in a rock band, giving him vampire fangs, and giving him a human girlfriend named Madonna, but Sega of America scrapped these ideas to keep his identity simple. Sega of America also expressed concerns that most Americans would not know what a hedgehog is and initially proposed a full-scale recreation of the character, but compromised with Sonic Team to simply make design changes. Robotnik ended up being named Dr. Eggman in Japan and Dr. Robotnik in other regions as a result of a dispute between Sega's American and Japanese divisions.
With a satisfying protagonist completed, Sega turned to esteemed programmer Yuji Naka, who had impressed them through his work on Phantasy Star and the Mega Drive port of Makaimura. The gameplay originated with a tech demo by Naka, who developed an algorithm allowing a sprite to move smoothly on a curve by determining its position with a dot matrix. Naka's prototype was a platform game with a fast-moving character rolling in a ball through a long, winding tube, and this concept was fleshed out with Ohshima's character designs and levels by designer Hirokazu Yasuhara. Yasuhara originally intended to work on the game for three months due to the delay of his planned move to the United States by the outbreak of the Gulf War, but was engrossed in the project for nearly a year. His designs for levels were intended to attract both hardcore and casual gamers by integrating occasional challenging set pieces into the mostly accessible level design. The game's color scheme was influenced by the work of pop artist Eizin Suzuki, and the aesthetics of Green Hill were influenced by the geography of California.
In designing the game mechanics, Naka was inspired by Shigeru Miyamoto, whose games he had enjoyed playing years earlier. Admiring the simplicity of Miyamoto's mechanics in complex environments, Naka decided that Sonic would be controlled with only a directional pad for movement and a single button for jumping. He also wanted his creation to be more action-oriented than the Mario series; while playing Super Mario Bros., he had wondered why the levels could not be cleared more quickly. Due to the need to demonstrate the Mega Drive' technological promess, the developing game underwent extensive testing and redesign, a process taking over six months. The developers' efforts were rewarded; according to Yuji Naka, the game had the fastest-ever character speed in a video game and a rotation effect in the special stages that was considered impossible on the console. The team intended to add a two-player mode displayed via split-screen, but Naka's programming knowledge was insufficient to implement this feature. However, such a mode would later appear in sequel Sonic the Hedgehog 2 (1992), where the second player would control Sonic's best friend Miles Tails Prower. Naka, Oshima, and Yasuhara worked 19 hours a day on the project for several months.
Naka's relationship with Sega of Japan was tenuous during this time; he received little credit for his involvement in the game. He left the company shortly after the game's release, although Sega of America hired him later. Before leaving, however, he went against Sega of Japan's prohibition of him including post-game credits by including a few names in black text on a black background, identifiable only by looking at the game's code.
Known export releases :
"Sonic the Hedgehog [Model 1009]
"Sonic the Hedgehog [Model 1009-50]
"Sonic the Hedgehog [Model 1009-22]
"Baramdori Sonic [Model GM4015JG]" by Samsung Software
"Sonic the Hedgehog
" by Tec Toy