Mighty the Armadillo in Sonic the Hedgehog (aka Mighty in Sonic 1) is a hack of Sonic 1 by E-122-Psi, starring Mighty as the playable character instead of Sonic the Hedgehog. The game is modified to use Mighty's sprites in place of Sonic's, along with several modifications to the player's stats and abilities.

Motobug the Badnik in Sonic the Hedgehog (aka Motobug in Sonic 1) is a hack of Sonic the Hedgehog for the Sega Mega Drive, by Polygon Jim. As its title suggests, in this hack the main character Sonic the Hedgehog is replaced by Motobug, one of Dr. Robotnik's badniks.So far, some of Sonic's main sprites and animations have been replaced by those of Motobug, Motobug's speed has been decreased (except when powered-up by aSpeed Shoes monitor, which are more numerous), and the sprites of Roller badniks in Spring Yard Zone have been replaced by those of Sonic (referencing a common interpretation by fans that Roller is a robotic impersonation of Sonic, something that officially appeared in later games in the form of Metal Sonic and various others).Of the first release, Polygon Jim stated that he had only tested and confirmed Green Hill Zone (Acts 1-3) for completability. However, upon testing, Katelynn andRGamer2009 reported that other Acts are completable, including:Marble Zone Act 1Spring Yard Zone Acts 1 and 2Labyrinth Zone Acts 1 and 2Star Light Zone Acts 2 and 3Final Zone

Sally Acorn in Sonic the Hedgehog (aka Sally in Sonic 1) is a fan-made ROM of the game Sonic the Hedgehog for the Sega Mega Drive/Genesis, with Princess Sally Acorn as a playable character in place of Sonic the Hedgehog.The game was modified by Sonic Retro member E-122-Psi, with additional programming and coding by other members including Snkenjoi,MarkeyJester, Aquaslash,Selbi and Hayate.

Sally Acorn in Sonic the Hedgehog 2 (aka Sally in Sonic 2) is a fan-made ROM of the game Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis, with Princess Sally Acorn as a playable character in place of Sonic the HedgehogThe game was modified by Sonic Retro member E-122-Psi, with additional programming and coding by other members including MainMemory, Qiuu and Snkenjoi.

Vector the Crocodile in Sonic the Hedgehog (aka Vector in Sonic 1) is a hack of Sonic 1 by E-122-Psi, starring Vector the Crocodile as the playable character instead of the blue hedgehog. The game is modified to use Vector's sprites (edited from Knuckles Chaotix) in place of Sonic's, along with several modifications to the player's stats and abilities.The game was modified by Sonic Retro member E-122-Psi, with additional programming and coding by other members including MarkeyJester and flamewing.