May 14, 2024 12:00:00

Super Mario 64's 'unopened door' opens after 28 years

In the course 'Cold Cold Mountain' that can be entered early in the game '

Super Mario 64 ,' there is a door to a hut that can be opened from the inside but never from the outside. This door has been known as a 'locked door' since the game's release in 1996, but it has now been reported that it can actually be opened.

SM64's Unopenable Door Has Finally Been Opened! - YouTube


At the starting point of Cold Cold Mountain, there is a hut with a chimney like the one shown below. If you enter the hut from this chimney, you will be transported to a stage with a long ice slide called the 'Snow Slider.'

The goal of the Snow Slide is a room in a mountain hut. There is a door leading outside, and if you open it, a 'Power Star' will appear.

However, the door that you just opened is designed so that it cannot be opened from the outside, and you cannot return to the hut through the door. This is the true nature of the 'locked door.'

The person who reported opening this door was a Super Mario 64 TAS player named Alexpalix1. In response to this report, YouTuber pannenkoek2012 explained how to open the door and why it is designed not to open.

According to pannenkoek2012, the problem is not that the door doesn't open at all, but that Mario simply can't touch it. The reason is that there are walls with collision detection around the door, as shown below, which prevents Mario from getting close to the door.

Apparently if you modify the game and remove the collision detection on walls, you can open the door normally.

So how can you open the door without modification? pannenkoek2012 also explains this.

In the game, the collision detection for a door develops in a circle around the door, and if Mario can touch this collision detection, the door will open.

However, there is a wall around the door in question, and because of the collision detection for the wall, it is impossible to touch the door from outside the hut.

But what if you're inside the shed? If you can somehow slip through the wall, you might be able to touch the collision box on the inside of the shed.

The penguin nearby will come in handy here. This penguin is looking for lost children, and if you find a baby penguin and take it with you, you will receive a Power Star as a gift, but if you steal the baby penguin, he will get angry and chase you. The penguin has a collision detection function, and Mario can go through the wall by being pushed by the penguin.

If Mario was simply pushed out, he would hit the wall and shift sideways, so you need to place the penguin as close to the wall as possible and have Mario do a flip between the wall and the penguin.

This technique allows Mario to go through walls, but since there is no floor inside the wall, he will fall. Doors don't open while falling, but open while walking, so even if Mario touches the door's collision detection, it won't open if he is falling.

Here, Alexpalix1 used the technique of 'changing Mario's direction immediately after landing.'

Internally, the code to 'walk' is executed immediately after Mario turns around, and the code to 'free fall' is executed when Mario leaves the ground. However, it seems that the programmer did not expect the code to 'free fall' and the code to 'change direction' to be executed in the same frame, so there is a bug in which the action of 'walking' is executed only for one frame when the action of free falling and changing direction is performed at the same time.

By touching the door's collision detection during this one frame, the door will be opened.

By the way, it seems that using this technique does not shorten the time it takes to clear the level.