SMB3 also has an interesting tool assisted speedrun (non-human doing the inputs) where fast inputs on the second controller cause an overflow on the input buffer allowing for the game to be beaten basically instantly from the start screen.
If you like this because of the interesting stuff done to abuse the game The Legend of Zelda Ocarina of Time has pretty much been a history of "and then a quicker way to corrupt the game was found".
It's not always about going fast either, challenge runs also get a lot of very interesting results from a lot of dedication. Super Mario 64's A Button Challenge (try to beat the game with as few A presses as possible) has tons of outrageously complex tricks with amazing explanation videos. One in particular caught people's attention to the point it became a meme https://www.youtube.com/watch?v=kpk2tdsPh0A though it's not actually the most technically impressive to come out of that endeavor.