Tremendous Mario Bros 2 participant crashes the sport, casually posts the clip online, and by accident makes “the largest 2D Mario speedrun discovery in years”

A significant and exceptional finding in the realm of 2D Mario speedrunning has occurred, all due to an entirely unintentional gameplay clip that a casual participant decided to share online.

On March 13, an individual named Luigi’s Sidekick shared a series of clips on Twitter while playing through the Japanese Super Mario Bros. 2 – better known to most English speakers as The Lost Levels – via the Nintendo Switch Online NES catalog. In one of those clips, the game unexpectedly crashes during the final stage, 8-4, leading to a message from the Switch interface stating that “an error has occurred in the game,” followed by an abrupt return to the game selection screen.

After several weeks of silence, the video caught the attention of Mario speedrunners, who noted that this glitch could potentially lead to a method for arbitrary code execution, or ACE. This glitch effectively places SMB2’s purchasing code in restricted areas, and by manipulating aspects of memory in specific ways – for instance, ensuring enemies are positioned correctly or having a particular set of codes – one could potentially input a cheat code that warps the player to the ending.

Mario speedrunner Kosmic – the same Kosmic who recently discovered that the famed kill screen in Donkey Kong isn’t truly the end – humorously remarked that it might take a “few… months” to fully analyze what’s going on here. However, if you seek a “very brief” summary of the explanation: “If you arrange all the object slots in a certain order, the long firebar can be loaded from out-of-bounds memory,” Kosmic clarifies. “Doing it a second time can write even further out of bounds and trigger a chain reaction that would typically crash the game, but with high precision, it can succeed.”

Within days of the Mario speedrunners identifying the glitch, they successfully replicated it and developed a method to utilize ACE to warp to the conclusion of SMB2. Kosmic shared a clip of the warp created by fellow runner threecreepio on Twitter, labeling it “The Biggest 2D Mario speedrun discovery in years.” This instance was utility-assisted, as it is likely far too complex for a human to execute in real-time, however, the community appears optimistic that a practical method of performing this trick manually will be discovered.

The catch here is that this ACE exploit only functions in 8-4, which again, is the game’s last stage. The trick is ultimately only capable of saving between 10 to 15 seconds, yet that is still quite substantial for a well-established game like this. The previous world record – which was set by Niftski all the way back in 2022 – might still hold, as it’s likely the game’s any% category will be divided into ACE and non-ACE variations if a human-executable method for this trick is figured out.

“I genuinely can’t believe that a random crash I experienced with this game actually led to uncovering a new speedrun technique,” Luigi’s Sidekick mentioned on Twitter after the ACE exploit was revealed. “How on earth did I manage to do that?”

Another amusing aspect: the glitch happens just as Mario falls into a lava pit upon striking a fortress wall. This is the exact imagery featured on the North American cover art for the original Super Mario Bros., and as some viral tweets have shown.