This is my flip-flop mod for the SNES. It adds a menu option to randomly swap controls between players 1 and 2, including single-player games. There's a countdown timer so you know it's coming.
Forked from the official Snes9x repo.
Compile the Windows version yourself from the source code, or download the executable here. Be sure countdown.wav is in the same directory as the executable, or you'll get a default Windows sound instead. If you don't like the sound, you can make your own. Just name it countdown.wav and put it in the same directory and it will work.
To see me and my brother test it out with a playthrough of Mega Man X, check here.