Wow. just wow. I used to go through the original Super Mario Bros. game pretty quickly… but this guy takes it to the next level. Using a single controller, various emulators, and some save states, Youtube user agwawaf was able to beat the first four Mario games… all at the same time!!
The trick is that this is a tool-assisted speedrun — using emulators, save states, and running the games at a very slow pace, he was able to individually tweak and nudge each movement of the four Marios so that they would stay a hair’s breadth from danger. It’s still a remarkably impressive achievement when you consider the painstaking care that such a meticulous feat would require. [Source]