The difference between Kosmic and HappyLee is approach. Kosmic’s world record happened in real-time, forcing him to string together a nearly perfect run of the game without a chance to recover. HappyLee, however, performed a tool-assisted run (TAS), in which the goal is to program a series of inputs that maximizes the speed at which a given game is played, typically in a way that would be impossible for humans to copy. In essence, you're not playing the game, but scripting the game to play itself.

It’s unclear how long Kosmic’s record will hold. Super Mario Bros. speedrunning is at a fascinating moment; every new record brings people one step closer to reaching what’s believed to be the fastest possible time for a human to beat the game: four minutes, 54 seconds, and 32 milliseconds. That record was set in 2011 by speedrunner HappyLee , a time that stands about two seconds faster than what Kosmic just achieved.

“Oh my gosh,” muttered Super Mario Bros. speedrunner Kosmic , as he snaked through a tough section of 8-4, the final stage in the game. “C’mon, man.” Moments later, he jumped over Bowser’s hammers, dropped his controller to the ground, and began to process the enormity of the moment.

The time saved is roughly 1.3 seconds, but the inputs are so precise speedrunners believed it was either A) so difficult it wouldn’t be reasonable to incorporate into record runs or B) simply beyond human ability. 1.3 seconds or not, they gave up.

“The Flagpole Glitch is performed by grabbing the flagpole at the end of stage while Mario is inside of the block that the pole sits on,” explained Darbian. “Mario normally remains on the flagpole until the flag drops to the bottom at which point he hops off and walks to the castle. The Flagpole Glitch skips the animation of the flag coming down and allows Mario to immediately get off of the pole, saving a little bit of time.”

The most significant discovery in the last several years is the Flagpole Glitch, a trick discovered as part of improving TAS. It involves using specific inputs at specific frames.

“As the time in any game lowers,” said Darbian, who held the previous Super Mario Bros. run, before Kosmic beat him by 66 milliseconds , “the options for improving it further become more and more limited. For less studied games, sometimes the best approach is to do more research and testing to possibly find a new route or new trick to employ to save more time. In the case of Super Mario Bros., the game has become about how many of the TAS strats can a person incorporate into a single playthrough.”

All told, this revelation shaved a second off human speedruns, helping catch up to the elusive TAS. The evolution of Super Mario Bros. world records always involves a push-and-pull between these two related, but wholly different, realms of speedrunning.

A speederunner named Sockfolder did some emulator digging, hoping to come up with a path for humans to pull off the Flagpole Glitch. He did, and speedrunners were soon able to deploy the glitch on several levels: 1-1, 4-1, and 8-3. Other stages allow the glitch, but don’t actually save time, due to what’s called “frameruling.” The game’s coded in such a way that you can only save time in increments of 21 frames, or roughly every 0.35 seconds. At times, this interferes with the Flagpole Glitch, nulling its effect, which means there’s no reason for a speedrunner to risk messing up an attempt.

Darbian explains the extremely technical but very interesting problem: "The biggest hurdle we faced was that the clip was only possible if you had certain ‘subpixel’ values. Subpixels are positional data in memory that are not reflected on-screen. Basically, the screen will render Mario on a certain pixel, but internally his position could be fractions of a pixel off. The subpixel data is constantly changing as Mario moves, but it always starts out at a consistent value when a new room is loaded, and if you simply hold right and B to run, it will change in the same way every time. Unfortunately in 1-1, simply running and jumping to the block that the flagpole sits on does not yield good subpixel values to make the clip possible.”

He deployed the Flagpole Glitch at 1-1 and 4-1, but skipped it on 8-3. By contrast, Darbian used the Flagpole Glitch at 1-1 and 8-3. But when the two enter 8-4, the final level in Super Mario Bros., their times are actually identical. The crucial difference was Kosmic’s performance on 8-4, the moment when most speedrunners lose their cool.

For about 30 minutes before a run, Kosmic practices the hardest tricks, trying to internalize the movements. This builds on the hours he’s spent playing via save states. A common tactic among speedrunners, save states allow you to reload a specific sequence in the game—like trying to use a glitch—and run through it over and over again instantaneously, instead of having to play the game again.

Kosmic, who asked to keep his real name private, has been speedrunning since late 2011. He got started by mimicking glitches and tricks on YouTube, and originally concluded speedrunning was too hard. He stuck with it, though, and eventually streamed Super Mario Bros. for the first time on the Twitch channel SpeedRunsLive , where he finished in one hour, 10 minutes, and 18 seconds. In the roughly six years he’s been playing since, he’s shaved more than an hour off that time.

"Your heart feels like it's going to explode the closer you get to the end," said Kosmic. "It doesn't help that 8-4 is one of the hardest levels. In 2017, I lost about 20 world record-pace runs to the second room in 8-4. As disappointing and frustrating as that was, I think it really has helped my mentality in those situations. I finally finished a run on that pace at the end of 2017, and since then have been able to close out every run that has gotten to 8-4 on crazy pace."

“Many of the top runners have experienced that pressure multiple times,” said Darbian, “and now that we're going so many extra strats during the earlier levels, the pressure on 8-4 is really intense. The 8-4 that Kosmic acheived in this record wasn't just great—it was truly remarkable.”

It’s possible, of course. You can add another risky Flagpole Glitch to 8-3, and clip through a wall at the end of 1-2. If you were to do both, you could end up at 8-4 faster than both Kosmic and Darbian, and give yourself a chance at getting the record.

“I am not sure many people would be dedicated enough to go through the tens of thousands (or more) attempts needed to even get the chance at saving that time [for a perfect run]."

Someone will beat Kosmic eventually. It might even be Kosmic himself, who anticipates a return to Super Mario Bros. speedrunning "in the future." Darbian speculates the best a human could achieve, based on everything we know about Nintendo’s platformer, is four minutes, 55 seconds, and 5X milliseconds. (The X is because Darbian doesn’t know; it’s an estimate.)