The game starts when Dr. Robotnik comes up in his UFO, and kidnaps a bunch of guys Sonic doesn't know. Sonic runs after him, but Robotnik is too fast. So, Sonic has to beat a bunch of "zones" to get to Robotnik. Each stage is filled with some of Sonic's new friends turned into robots. He tries to kill them, but he just releases them, so he gets sad. Then, he gets mad. So he attacks Robotnik, and defeats him. Robotnik says "I'LL GET YOU SONIC!", and he falls off a cliff. But then his UFO picks him up, and he flies off into space. Then the words "THE END" appear. Then the words "REALLY, GET OUT OF HERE" appear. Then the game shuts off.
Despite the fact that you have to play this game for twenty-four hours straight to win the game, it was very popular. Everyone demanded a sequel, so one was made.