Super Mario 64's Secret Door Is Finally Opened After 28 Years Without Any Mods
The 28-year-old game's mechanics were well understood long before that existed, though, thanks to the efforts of speedrunners like the legendary pannenkoek2012. You've probably heard of this fellow before; he's the man who became infamous for introducing the concept of the "half A-press" to Mario 64 speedrunning.
One of the most enduring mysteries surrounding Super Mario 64 has centered around a door in the Cool, Cool Mountain world. You see, you start Cool, Cool Mountain at the top, and right near the start area there's a building you can enter. Doing so will put you inside an indoor area with a large slide that takes you to a similar shack at the bottom of the mountain. However, the door out at the bottom is a one-way door; once you leave, you can't come back.
You have to be both walking and inside the red circle to open the door.
Except it's been known for some time that the door actually isn't a one-way door at all. There's a functioning door entity there; you just can't reach it because the hitbox for the wall pushes you away. Clipping through the walls in Mario 64 isn't exactly difficult, but there's another problem: there's no ground inside the shack if you enter from the outside. Clipping through simply causes you to fall to your doom—there's no way to activate the door.
As you've no doubt guessed, an enterprising player has now figured out how to use the door. User "Alexpalix1" on Discord posted a short video demonstrating how to do it. The method is fairly simple, and combines two known techniques—a clip exploit involving the penguin mama, and a "turn around" frame exploit in Super Mario 64's code.
By activating a "turn around" animation in mid-air, Alexpalix1 was able to trick the game into triggering the door animation just as Mario enters his free-fall. As pannenkoek2012 explains quite succinctly in his video, Mario still passes through the kill plane that would normally force him to reset, but because he's in the door opening "cutscene" animation, it doesn't affect him, and he passes through the door normally.
