What is the name of the first zone in Sonic the Hedgehog (1991)?

The first zone in Sonic the Hedgehog (1991) is Green Hill Zone. It introduces players to Sonic's fast platforming through a bright, grassy landscape filled with palm trees, loops, ramps, springs, cliffs, and Badniks.

Green Hill Zone is located on South Island and contains three acts. The third act ends with a battle against Dr. Robotnik, after which Sonic proceeds to Marble Zone, the game's second zone. The level's natural setting was influenced partly by California, while its checkerboard ground and bold colors helped define Sonic's visual identity.

A common mix-up is Emerald Hill Zone, which is the first zone in Sonic the Hedgehog 2, not the original 1991 game. Green Hill Zone became one of the series' signature locations and later returned in games including Sonic Adventure 2, Sonic Generations, Sonic Mania, Sonic Forces, and Sonic Frontiers.