This one is likely more heard of, and by that, it was a ROM hack of a bootleg named Somari which made you Sonic and started you off at Spring Yard Zone. For this cassette, I am using the "improved version", which fixes some glitches and music. It's also pretty surprising that they fit this game (being 16bit) on an 8bit console. But what's weird is, like the existing Super Mario World port, this one is 768kb, and Sonic the Hedgehog is 512kb! Things just puzzle me sometimes.