Later games added a large cast of characters some, such as Miles 'Tails' Prower, Knuckles the Echidna, and Shadow the Hedgehog, have starred in spin-offs. Games typically feature Sonic setting out to stop Eggman's schemes for world domination, and the player navigates levels that include springs, slopes, bottomless pits, and vertical loops.

While Sonic games often have unique game mechanics and stories, they feature recurring elements such as the ring-based health system, level locales, and fast-paced gameplay. Sega exited the console market and shifted to third-party development in 2001, continuing the series on Nintendo, Xbox, and PlayStation systems. After a hiatus during the unsuccessful Saturn era, the first major 3D Sonic game, Sonic Adventure, was released in 1998 for the Dreamcast. A number of Sonic games were also developed for Sega's 8-bit consoles, the Master System and Game Gear. Sega Technical Institute developed the next three Sonic games, plus the spin-off Sonic Spinball (1993). Its success helped Sega become one of the leading video game companies during the fourth generation of video game consoles in the early 1990s. Naka, Ohshima, and Yasuhara developed the first Sonic game, released in 1991 for the Sega Genesis, to provide Sega with a mascot to compete with Nintendo's Mario. The franchise also incorporates printed media, animations, feature films, and merchandise.

The main Sonic the Hedgehog games are platformers mostly developed by Sonic Team other games, developed by various studios, include spin-offs in the racing, fighting, party and sports genres. The franchise follows Sonic, an anthropomorphic blue hedgehog who battles the evil Doctor Eggman, a mad scientist. Sonic the Hedgehog is a Japanese video game series and media franchise created by Yuji Naka, Naoto Ohshima, and Hirokazu Yasuhara for Sega.

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