The Sonic 3 Angel Island Revisited project (often referred to as AIR) is the most popular reason to need this file. Download Sonic 3 AIR. Run Sonic3AIR.exe .
In the mid-1990s, Sega planned to release Sonic the Hedgehog 3 as a massive, single game. Due to time constraints and production costs, they split it into two cartridges: Sonic the Hedgehog 3 (16-bit, 1994) and Sonic & Knuckles (1994).
Plug your physical Sonic & Knuckles cartridge into the Retrode. Lock your physical Sonic 3 cartridge into the top of it. Connect the Retrode to your PC via USB.
Highly accurate, widely available via RetroArch.