Sonic the Hedgehog 4: Episode I is a 2010 side-scrolling platform game developed by Dimps, with assistance from Sonic Team, and published by Sega. It is part of the Sonic the Hedgehog series and acts as a sequel to Sonic & Knuckles (1994). Episode I follows Sonic as he sets out to stop Doctor Eggman, who has returned following his defeat in Sonic & Knuckles. The game returns to the Sega Genesis style of Sonic gameplay, with movement restricted to a 2D plane. Like previous Sonic games, the player races through levels, collecting rings while rolling into a ball to attack enemies. The game also features special stages in which the player collects Chaos Emeralds and online leaderboards comparing level completion times and high scores.
