The Sonic 3 & Knuckles Steam ROM is a modified version of the original game, allowing it to run on PC through the Steam platform. The ROM is based on the original Sega Genesis game and has been optimized for modern hardware.
If you already own an original Sega Genesis ROM file from a legitimate backup (e.g., from your own cartridge), you can play it on PC using emulators like or RetroArch —but you must not download ROMs from unauthorized websites. sonic 3 knuckles steam rom