Super Mario Bros. Has a New Glitch After 40 Years
Speedrunner Kosmic discovers first ACE in original Super Mario Bros. – breakthrough after four decades.
Imagine this: the original 1985 Super Mario Bros., played by millions, dissected by tens of thousands of speedrunners, and yet it still holds secrets. This is not fantasy—it's a fact that shook the community in April 2026. Speedrunner Kosmic documented something thought impossible for 40 years: the first arbitrary code execution (ACE) in a clean, unmodified Super Mario Bros. on NES.
What is ACE and why is it so important?
ACE is the holy grail of exploits. It allows injecting custom code into the game, bypassing its original logic. In practice, this means you can do virtually anything—from instantly finishing the game, accessing hidden worlds, to altering rules on the fly. ACE has been used in games like The Legend of Zelda: The Wind Waker and Pokémon series, but in the original Mario? No one thought it possible.
“If you want, you can now access not just the Minus World, but any world or level you want. No hacks or cheats. It's a glitch that makes anything possible.”— Kosmic (speedrunner)
How did it start? From a crash in Switch Online
The story begins not in the original, but in an emulated The Lost Levels on Nintendo Switch Online. Twitter/X user @TheLuigiSidekick experienced a catastrophic crash during a speedrun attempt. The speedrunning community, seeing the footage, immediately wondered: what if that crash isn't an emulator bug but a key to something bigger? That was the first, barely noticeable tremor that started an avalanche.
Finding a needle in a haystack: 40 years of code
The breakthrough came when researchers stopped treating the crash as an endpoint and began using it as a starting point. For weeks, they tested hundreds of hypotheses, manipulating Mario's positions, enemy counters, and NES memory. They wanted to find a way to force the game to read data from RAM as processor instructions. This is work on the edge of hardware and logic, requiring an understanding of how the 40-year-old 2A03 chip processes data.
Connect this to something concrete: Kosmic and his collaborators used a previously known object limit bug, but in an unprecedented way. They managed to exceed the memory allocation limits for objects in the game, so data from one object was read as processor instructions. This was not an accident—it was a precise operation at the level of zeros and ones.
What exactly can you do with this ACE?
For now, the practical application is limited. Using ACE to skip to the ending screen is slower than a classic speedrun. It also requires pixel-perfect inputs that even the best speedrunners may not execute consistently. But that's not the goal. The goal is proof of possibility.
What does this mean for us? Now the community knows the boundary isn't glass. You can inject code that changes the game's rules on the fly. Could this open the door to skips that shave minutes off records? Maybe. But for now, the priority is exploration: what else can be changed in the game's memory? Can you force it to load a different level? Or change enemy behavior?
Why is this a breakthrough after 40 years?
Super Mario Bros. is an icon. It's one of the most important, most analyzed games in history. We thought we knew every pixel, every frame, every bug. Discovering ACE changes that narrative. It shows that even in the most (culturally) perfect game that survived four decades, you can still find new layers. This isn't just a glitch—it's a philosophical challenge to all of retro-gaming.
This is a real problem for traditional speedrun categories. If ACE becomes practical, will a new “ACE Any%” category emerge? How will this affect records? The community is already debating. Kosmic suggests it's more about “the achievement of making it possible and solving it” than immediately breaking the meta.
What's next? A new era of research
Now the real fun begins. With the ability to inject any code, speedrunners can experiment with truly radical skips. Can ACE be used to finish the game in under 5 minutes? Can a script be created to turn the game into something completely different? This opens doors to research reminiscent of speedrunning's early days, when every day brought a new discovery.
Look at this from a game preservation perspective too. ACE shows that even the most closed, dissected systems have hidden hatches. It's a reminder that certain aspects of old software are unpredictable—and that's precisely why they're fascinating.
Is this the end of certainty? No. It's the beginning of a new chapter. Super Mario Bros. still has secrets, and we're only starting to understand them. Kosmic and the community have proven that after 40 years, you can still do something that changes everything.
Who discovered this glitch?
Speedrunner Kosmic documented the community's find, which started from @TheLuigiSidekick's crash in The Lost Levels on Switch Online.
Can ACE be used in competitions now?
Not currently. It's a theoretical breakthrough, not a practical shortcut. Execution speed and reliability need major improvement.
