Sonic the Hedgehog ReOne is likely another fan-made ROM hack that modifies the original Sonic the Hedgehog game. It's unclear what specific changes or additions this ROM hack includes, but it likely builds upon the existing gameplay of the original. Without more details, it can be assumed it is similar to other fan-made projects. It is a fan-made creation and is not officially affiliated with SEGA.

Sonic the Hedgehog ReOne

Sonic the Hedgehog Painful World Spikes Kazio Megamix