From Sonic Retro
Sister Sonic is a canceled localization of Popful Mail announced sometime in 1993. Originally the plan was to replace the existing cast of the game with Sonic characters, including Sonic's long lost sister, Sister Sonic. Due to a large number of angry letters sent to Sega Falcom (the name which would be used for the Sega and Falcom team) it was decided to cancel this port and instead settle on a more direct port of Popful Mail to the Mega CD.
|Unreleased Sonic the Hedgehog Games|
Sonic's Edusoft (Master System)
Sonic Sports (Sega 32X)