Over a year ago, an ordinary player stumbled upon a crash while playing the Japanese version of Super Mario Bros. 2 on Nintendo Switch. In itself, that's not such a wild thing – even old games crash now and then – but the specifics of this glitch turned out to have massive implications for the speedrunning community. This ended up being the first step in essentially reprogramming the game as it runs to do anything you want, and now, after a year of work, speedrunners have applied those lessons to the original Super Mario Bros. as well.
This glitch is a door to arbitrary code execution. ACE exploits take advantage of bugs in a game's code to input new instructions that were never intended by the original developers, opening the door to all kinds of wild shenanigans. Speedrunners, for example, might use ACE to warp directly to a game's end credits.
