Sonic 2: S3 Edition is a ROM hack of Sonic the Hedgehog 2 for Sega Genesis, likely created within the ROM hacking community. The original Sonic the Hedgehog 2, released in 1992 by Sega, was a pivotal game in the platforming genre.  This hack aims to incorporate elements reminiscent of Sonic 3, its sequel.  Information about specific changes is scarce, but it probably alters graphics, level design, music, or gameplay mechanics to resemble the feel of Sonic 3. It would keep the core Sonic 2 gameplay loop but make visual or mechanical changes to bring it closer to Sonic 3's style.

Sonic 2: S3 Edition