Mecha Sonic in Sonic the Hedgehog (aka Mecha Sonic in Sonic 1) is a hack created as a proof-of-concept by Iron Sonic of Sonic the Hedgehog for the Mega Drivein which the player plays as Mecha Sonic from Sonic & Knuckles. The controls are the same as in the original Sonic 1, save for the ability to perform the Spin Dash. Each sprite has been edited, and the player size and other aspects of the Sonic object have been changed to accommodate Mecha Sonic's larger size.

Whilst the game is mostly playable, there are certain areas in the game that Mecha Sonic cannot complete due to his increased size; prime examples of this includeSpring Yard Zone and Scrap Brain Zone.