A 40-Year-Old Breakthrough
Forty years after launch, Super Mario Bros. just surprised its most dedicated players. The speedrunning community has confirmed arbitrary code execution in the original NES classic, a feat many assumed was out of reach. On Tuesday, veteran runner Kosmic posted a YouTube breakdown of the new glitch, calling it a major step for future experiments—even if it won’t topple records right away.
Arbitrary code execution, or ACE, lets players feed custom instructions into a game using only controller inputs and in-game actions. Other franchises have used similar exploits to skip huge chunks of content—think The Legend of Zelda: The Wind Waker, various Final Fantasy entries, and numerous Pokémon titles. Mario games have seen ACE before, but the first game in the series had resisted it until now.
How It Happened
The spark came from an unexpected place. According to Kosmic, the team first suspected something new when Twitter/X user @TheLuigiSidekick crashed The Lost Levels on Nintendo Switch Online during a routine playthrough. That footage set off a wave of testing. Runners dug into memory behavior, tried to reproduce the conditions, and chased a path to the same kind of instability in the original Super Mario Bros.
After trial and error—and plenty of guesswork—the community found a narrow setup that lets players bend the game’s logic. The result is full ACE in SMB1. In practical terms, it means you can make Mario jump straight to the game’s finale. Yes, credits warp in the original NES release is possible without external hardware, patches, or save-file tampering.
“If you want, you can now access not just the Minus World, but any world or level you want,” Kosmic told Polygon. “With no hacks or cheats. It’s a glitch that makes anything possible.” For a game that’s been dissected for decades, that’s a startling sentence.
What It Means For Speedruns
Don’t expect a new any% world record tomorrow. Kosmic cautioned that the method is narrow and execution-heavy, relying on tight, pixel-precise inputs that leave little room for error. Even when performed correctly, the current route to credits is still slower than beating the game through standard techniques. That puts it outside the realm of immediate leaderboard impact.
“More so about the achievement of making it possible and solving it,” Kosmic told Polygon, framing the discovery as a technical milestone rather than a record-chaser. If runners do optimize it, the community would likely treat ACE as its own category to keep traditional records comparable. That mirrors how other scenes handle large exploits: document them, race them, but don’t let them override long-standing categories.
For context, SMB1 speedruns have lived near mechanical limits for years. Runners already nail frame-perfect tricks, manipulate enemy cycles, and route levels down to the pixel. The shared sentiment has been that there’s not much left to uncover. ACE flips that idea on its head—maybe there’s still room to write “new” rules inside this old cartridge.
Why It Matters Next
Access to ACE in SMB1 gives tinkerers a fresh sandbox. Tool-assisted runners can map new memory setups; real-time runners can hunt for safer alignments; glitch hunters can aim beyond the familiar Minus World and build reliable level warps. None of this guarantees faster completions, but it does expand what players can make the game do—legally, on unmodified software, using only controller inputs.
This breakthrough also arrives during a rocky stretch for the Mario speedrunning scene, which has dealt with its share of drama. A community-wide solve like this is a welcome counterpoint—a reminder of what collaboration can produce when folks chase the same mystery. It’s already sparked healthy debate about categories, verification, and best practices for documenting complex glitches.
I’m curious where it lands next. Maybe someone finds a setup that trims the inputs, stabilizes the memory state, and inches ACE toward real-time viability. Maybe this becomes a playground for custom level routes and educational showcases. Either way, a 1985 platformer just handed its experts a new puzzle, and that kind of surprise tends to lead somewhere interesting.
