Sonic the Hedgehog 2 is a 2D platformer released in 1992 for the Sega Mega Drive. It features Sonic running through colorful, themed zones to collect rings and defeat bosses. New features include special stages to collect Chaos Emeralds, allowing players to transform Sonic into Super Sonic. The game improved on the first Sonic game and was a commercial success, helping Sega compete with Nintendo in the video game market during the 1990s.