Reaperman

There's a lot about reading an nes controller with an arduino--couldn't be that hard to get it to be the thing that output to nes instead, and read from a different source. It's probably best to do something with established timings from within the controller rather than just the switch-to-ground type of controllers which don't output at regular intervals.

There would be zero errors, no need for sync, raw recording. And it is not cheating either, it is recording a human use a joystick.

I wonder if anything is random in super mario, for example. I bet everything from pressing start on through the end could be recorded. It would probably still be best to replay only on the system it was recorded on though.