Super Mario 64 is still revealing design secrets after almost 29 years – but this one takes 14 months to uncover yourself

We love discovering little design secrets (or accidents) in video games, and incredibly Super Mario 64 is still delivering almost 29 years after its release for Nintendo 64 back in 1996. The landmark game is best known for introducing 3D Mario gameplay, but what happens if you stay in a scene for too long?

A dedicated fan has picked apart the code and discovered several ways to 'break' the the game. One of them reveals a hidden sound effect that's normally played only partially, while another will leave you trapped in the game for over two years.

If you want to indulge in more gaming nostalgia, see our pick of the best retro game consoles. Or for something bang up to date, see our guide to Nintendo Switch 2 preorders.

Mario 64 breaks after 7 days (And also after 4.5 years) - YouTube

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As Mario hacker Kaze Emanuar explains in the video above, games are designed with the assumption that you're going to be moving, exploring and interacting, not sitting still doing nothing for hours. Since they weren't designed for that eventuality, odd things can happen if you push their limits.

Kaze has found four such bugs in Super Mario 4. There's a ripping painting that stops rippling after 6.5 days, and a ship that stops flapping its wings after 14 months when its timer maxes out (in the Japanese version of the game).

Most catastrophically, there's a star select screen that could trap you for over two years if you happened to first wait two years to decide which star to select.

Kaze explains why such bugs occur in game design, often due to floating-point numbers (floats), which comprise exponents and multipliers, or intergers and timers that don't reset. He also looks at the precautions developers take to try to prevent these bugs.

In the case of the star select screen, the timer "catastrophically overflows" and leaps to the largest possible negative number, preventing a star from being selected until it counts upward again to a count of 12 frames.

Perhaps the most fun of all the discoveries is what Kaze calls the Sushi the Shark bug. The shark animation plays a sound every 16 frames – until after 14 months, when the timer maxes out and stops. "Since usually every time it starts playing the sound, it interrupts the previous playback, doing this is the only way to hear the full sound effect, so we've kind of unlocked a secret sound effect no one else has heard before," Kaze says.

He believes there are probably similar bugs in many titles, even modern games made on engines like Unreal Engine 5. Finding them becomes more feasible with decompilation, which allows code to be searched for suspicious snippets.

Fourteen months, or even 6.5 days, might be more time than the average player would ever realistically spend in a game, let alone one scene, but this deep dive into the game's workings reveals the fascinating precision of game design. And, as Kaze, says, some fans might feel a "twisted joy" in making the game break.

For more secrets, see the story of the lost Super Mario 64 sequel and these Mario design secrets. You might also want to check out Super Mario World remade in Unreal Engine.