Sonic the Hedgehog 4 (?????????????4) is a 2010 (2010 in video gaming) episodic (episodic video game) platform video game (platform game) in development as part of the Sonic the Hedgehog (Sonic the Hedgehog (series)) series for the PlayStation Network, Xbox Live Arcade, WiiWare, and the iPhone OS. The game was first announced September 9, 2009 under the name Project Needlemouse,cite webfirst=Torlast=Thorsentitle=All-new 2D Sonic rolling out in 2010url=Interactivedate=2009-09-09accessdate= 2009-09-09 and its official name was revealed on February 4, 2010. The game is being developed by Dimps alongside members of Sonic Team and is intended to be a return to the roots of the Sonic series. As such, Sonic 4 is a 2D side-scroller using sprites that are pre-rendered from 3D character models; Sonic the Hedgehog (Sonic the Hedgehog (character)) is the only playable character in Episode I.

The game will be playable in up to 1080p high definition (high-definition video) on the PlayStation 3 and Xbox 360,cite webtitle=Sonic the Hedgehog Q&A url=Interactive date= 2009-09-08accessdate=2009-09-11 and will feature support for motion controls on the PlayStation 3 and Wii. On May 20th, 2010, Sega announced that Sonic the Hedgehog 4: Episode 1 was delayed to late 2010 in order to spend additional development time on tuning and balancing the game.