Sonic the Hedgehog 4: Episode I (ソニック・ザ・ヘッジホッグ4フォー エピソードI Sonikku za Hejjihoggu Fō: Episōdo Wan?) is a 2010 episodic platform video game in the Sonic the Hedgehog series. The game was developed by Dimps, with assistance from Sonic Team, and is intended to emulate the original Sonic the Hedgehog titles on the Sega Genesis.
Episode I was released in October 2010 for iOS, PlayStation Network, WiiWare and Xbox Live Arcade. A release for Windows Phone 7 followed in June 2011, for PC (via Steam) and Android in January 2012, for BlackBerry PlayBook in July 2012, and for Ouya in July 2013. A sequel, Sonic the Hedgehog 4: Episode II, was released in 2012.