Sonic the Hedgehog (Amiga fan game)
From Sonic Retro
This is a small demo released on the Amiga by Dual Crew Shining. There is only one endless level, with graphics from Green Hill Zone. There are no rings, no way to die, and no HUD. You can kill badniks merely by jumping before you get to them, regardless of whether or not you actually jump on them. Graphics seem to be redrawn from scratch rather than converted from the original.