Sonic the Hedgehog 2 is a 1992 platform game developed by Sega Technical Institute (STI) for the Sega Genesis. Players control Sonic as he attempts to stop Doctor Robotnik from stealing the Chaos Emeralds to power his space station. Like the first Sonic the Hedgehog (1991), players traverse side-scrolling levels at high speeds while collecting rings, defeating enemies, and fighting bosses. Sonic 2 introduces Sonic's sidekick Miles "Tails" Prower and features faster gameplay.