28 years later, unopenable door in Super Mario 64’s Cool, Cool Mountain has been opened without hacks

Doors, a notorious evil that haunts architects and game developers throughout all of time and space, usually work pretty simply in 1996’s seminal 3D platformer, Super Mario 64— all except one, which cannot be opened from the “outside.” The one-sided door missing an outside handle at the bottom of Cool, Cool Mountain‘s slide has bothered Mario 64 enthusiasts for nearly three decades— but finally, a hackless answer has been found to this dilemma.

This answer was found by Super Mario 64 speedrunner “Alexpalix,” inspired by a YouTube video by notorious Super Mario 64 multiverse engineer (really) and A-press expert Pannenkoek2012, which explains Mario 64’s invisible walls. Since one of those invisible walls prevents this door from being opened, Pannenkoek’s prior work explaining them was key to finally answering this old question.

Normally, doors in Super Mario 64 come in one of two varieties: “real” doors, which simply open and lead directly into the next room, and “fake doors,” with fake corridors behind that mask loading or warping zones. The door at the bottom of Cool, Cool Mountain is, of course, the latter kind, and you can exit through the door on any mission that gives you access to the slide—but you cannot go back inside. The developers were helpful enough to remove a handle from the door to indicate this, but why is it like this at all?

Simply put, the natural collision of the hut (collision, or how objects interact physically, is calculated separately in 3D games from graphics) prevents the player from reaching the door. While other doors in Mario 64 can be bypassed with the help of liftable objects, that trick is only useful on “real” doors and thus isn’t useful here.

Ultimately, the secret to getting through the door’s glitched collision was simply glitching the collision even more. By getting the large mother penguin that hangs out beside the hut in Cool, Cool Mountain to approach closely enough to the door, then flipping into a perpetual, accelerating falling state between collision hulls, the player can pivot into the normally unreachable door and open it. No mods are required!

Sufficiently Determined Madmen truly is a wonderful example of tech enthusiasm everywhere. And today, we see those same madmen are keeping the Nintendo 64 hardware and its legacy alive much longer than anyone ever anticipated.