The game 's success led Sega to develop an extensive media franchise . A 1992 sequel , Sonic the Hedgehog 2 , gave Sonic a best friend ( and sidekick ) named Miles " Tails " Prower and continued the fight against Dr. Robotnik . Sonic has generated dozens of additional games and a large cast of recurring characters ( keeping Sonic and Robotnik as mainstays ) , surviving the end of Sega console manufacturing after the Dreamcast . The series has ventured from platformers to fighting , racing , role @-@ playing , and sports games , and has expanded into anime and manga , cartoons and comic books , novels , and toys . Sonic the Hedgehog has become one of the best @-@ selling video game franchises of all time , with over 150 million copies sold by May 2014 . The game 's first stage , Green Hill Zone , has also been re @-@ purposed for use in several other titles such as Sonic Adventure 2 , Sonic Generations and the Super Smash Bros. series .