In 2002, someone on GameFaqs discovered something curious: there was a coin in Super Mario 64 on a course called Tiny-Huge Island. Not just any coin, though. This coin was different from all the other 191 coins on the level, because unlike the other coins, you couldn't actually collect it.
The coin on Tiny-Huge island isn't the only unobtainable coin in Super Mario 64. There's also a coin in Snowman's Land which is unreachable through normal means. Still, the Tiny-Huge island coin—which can be found underneath the ground, by a slope next to a metal ball generator—was dubbed "the impossible coin" by the community.
Folks racked their heads trying to collect this particular coin—a quick Google search shows many forum posts and YouTube videos over the years that detail potential strategies and attempts to nab the coin. Yet, despite over a decade passing by since the Impossible Coin's discovery, nobody seemed to be able to do it.
"The coin was most likely just overlooked by the game's programmers and wasn't supposed to be in the game," someone wrote on SM64, a website that tracked progress on the Impossible Coin.
But on June 2014, someone finally did it: they nabbed the impossible coin:
This clip, uploaded by pannenkoek2012, is a tool-assisted run.
"You see, when you exit water from the side, there's a single frame when Mario is able to jump," pannenkoek2012 explains in the YouTube video. "I take advantage of this by jumping and kicking in order to move myself towards the coin and collect it."
pannenkoek2012 reckons that collecting the coin might be possible without TAS, but "doing it right in real time would be very difficult and require lots of practice." Still, the fact the coin was collected at all is incredible, given that it took 18 years to do this. So much work over a single coin! But it's just the beginning for pannenkoek2012, it seems—because now they're trying to kill an impossible Goomba.