Sonic 2 Mania Style is a ROM hack that likely focuses on implementing aesthetic changes inspired by the Sonic Mania game. This could include updated visuals, graphics, and potentially even sound design, aiming to make Sonic 2 look and feel closer to the more modern Sonic Mania title.  It's a community-driven effort to bring a modern aesthetic to a classic game and not associated with Sega.

Sonic 2 Mania Style

Sonic 2 Mania Edition