Kill Code

The kill code, as it is affectionately called, is an urban legend about a cheat code floating around the internet that would permanently brick the user's copy of Super Mario 64. While the code itself has been lost to time, the rumour of the code still roams the internet through obscure online hearsay.

Details
The effects of the kill code vary from accounts, but most commonly depict the sky turning a bright shade of red and the textures being replaced with a mismatch of red, white and black. Some have attested that the textures are likely the ones used by the Mad Piano.

Upon activating the kill code, the music in game gets replaced by the carousel music of Big Boo's Haunt and that all in-game sounds come to a stop. All enemies are swapped with Boos, whose voice lines are the only thing unaffected by the code's muting of all noises. The player is incredibly susceptible to damage, dying in one hit to any source of damage that they take. Upon leaving the level through any means, they are immediately sent to the game over screen. Attempting to reload the save file will also lead to the game over screen.

The anomalous nature of the kill code is the fact that this behaviour does not appear to go away. Upon reloading the ROM with the kill code inactive, the player will still be sent to the game over screen no matter what file they boot up. The only exception to this, according to some, is using the level select code which will forcefully load a level.

Authenticity
The veracity of the kill code is debated amongst the Super Mario 64 faithful, especially because of the outlandish and borderline creepypasta-like nature to the code. While codes able to swap textures are not unrealistic in Super Mario 64, pulling textures as well as object data from other levels is considerably less easy to believe. However given the fact there are sources that claim the game crashed upon enabling the kill code, that could be a consequence of the unrealism of the code's properties.

The code itself, or at least an authentic working version of the code, has yet to be discovered online. Many insist that the code used to be found on IGN or GameFAQs back in the day, but no archive of this has been found. All rumoured "codes" to be the kill code never tend to work on emulators, with some speculating that they only work on older emulators. However this seems unlikely, and has not been tested.

Speculation
With the current information gathered about Super Mario 64's development, people have re-evaluated the presence of the kill code and its anomalous nature. People have theorised that the kill code is actually a boolean left within the game's code by a developer, which when activated will tap into the Personalisation A.I. and cause it to become unhinged, uncontrollably corrupting the game beyond recognition. This would explain away the anomalous and near-intentional nature of the kill code, however it fails to explain why the save files proceed to corrupt afterwards and why the corruptions are so specific.