If you own the original cartridge or a digital purchase from the defunct Wii Virtual Console or the original Steam release, downloading a ROM backup is generally considered fair use. If you own nothing, it is piracy.

If you type "sonic 3 and knuckles steam rom download best free" into a search engine, the first result for purists should always point toward

Once you have your .bin file (usually around 2MB – yes, it is that small), here is how to play it on your PC to replicate the "Steam" feel: