Sonic 1 - Large Levels Demo is a ROM hack for the Sega Genesis, likely focusing on expanding the scale of the original Sonic the Hedgehog levels. The "demo" suggests it might be an unfinished or incomplete project showcasing the changes in level design, which would otherwise follow the familiar gameplay style of the original game. This fan-made title is not a release by Sega.

Sonic 1 - Large Levels Demo

Sonic 1 - DSK Edition