How Tool-Assisted Speedrunning Reveals The Inner-Life Of Video Games

A screenshot of Scott's desktop with everything he needs while he plays.

How Do You Find Glitches

But how are these glitches even discovered in the first place? It was a big question I had for Scott, and one that doesn’t really have a concrete answer. Many of them were discovered by average players messing around in the game, either recorded or shared through word of mouth. Others, such as Tyler’s parallel universes, were discovered by popping open the hood and observing how Super Mario 64 works.

In one instance, a speedrunner had recorded a video where a bob-omb followed Mario before he turned and dove to grab it, causing the bob-omb to vanish and instantly appear nearby. “Four or five of us started trying to recreate this exact scenario,” Scott said. “But we didn’t know what was redundant and what was necessary for the glitch to work.”

Serendipitously, Scott remembered a somewhat similar glitch in which Mario can hold his hat and pick up other objects, causing them to teleport when he puts them back down. What Tyler and Scott discovered was that the variable (called the ‘holp’ or ‘held objects last position’) used to store the position of objects Mario is holding will retain the value of the coordinates of the last held object once Mario releases it—even if he enters a new zone. If Mario is holding an object but the holp isn’t updating to the object’s current coordinates, such as when Mario is holding his hat, then when he releases an object it will appear at the holp’s position, not where Mario puts it down.

This similar glitch led them to discover that if Mario grabs an object and bumps his head in the same frame, causing him to release the object, the holp won’t have a chance to update its coordinates, thus moving the object to the holp’s last position. Finally, the team had cracked ‘The Mystery of the Vanishing Bob-omb’. Now, manipulating the holp has become a strategy that Scott uses to shave a few ‘A’ presses off of his videos.

But no matter how a glitch is initially discovered, Scott and the team use the same process for documenting them. First, the glitch must be isolated and recreated. Secondly, it must be understood. Using Mupen64, a popular N64 emulator, Scott can create an .m64 file that records a sequence of inputs and plays them back in the emulator, duplicating the exact processing and rendering of the game. “If we have it on a file like that, I can give it to Tyler and he’ll look into the nitty-gritty code and look at what calls are making it happen,” Scott said.

Earlier this year, Scott became aware of a potential glitch when a Twitch streamer suddenly teleported a huge vertical distance without reason. Given the hardest part of not using the ‘A’ button is gaining height, Scott saw its potential as one of the biggest glitches ever discovered. Because Scott only had the video to go by, he spent hours trying to trigger the glitch. He’s even offering a thousand dollar bounty for anyone who could demonstrably recreate it. But months later, the problem remains unsolved.

Scott isn’t convinced it could be a true glitch, either. During his research, he discovered that hacking and changing a single bit in Mario’s vertical position at the same moment in the original video had Mario teleport upwards in a similar fashion . “If you change the last bit from a one to a zero, you get exactly what we saw,” Scott explained, adding that popular theories suggest a gamma ray entered the Twitch streamer’s computer and happened to flip the bit or that a malfunction in the cartridge caused the miniscule change.

Pure Versus. Tool-Assisted Speedrunning

One of the biggest misconceptions surrounding the TAS community stems from its origins as a form of speedrunning. It’s not uncommon to find people who turn their noses up at TAS, condemning it as cheating compared to the purity of traditional speedrunning. But to do so isn’t only reductive of the work and effort invested by these players, it’s fundamentally ignorant of the reason they do it. “The goal isn’t to show how good we are at playing the game, the goal is to show what’s theoretically possible,” Scott said. “I think a lot of people refuse to accept the difference.”

Perhaps this misunderstanding comes from the way that TAS can so often look like pure sorcery. Unlike speedrunning, much of what Scott accomplishes isn’t immediately understandable by the average observer, and so many dismiss it the same way you’d dismiss someone claiming they beat a game when all they did was turn god mode on.

After talking with Scott, it’s hard to not imagine him and his friends as more akin to scientists than athletes. Like our own reality, Super Mario 64 is ruled by a set of laws that govern the purpose and action of everything contained within it. What’s so fascinating is how much Scott is able to do not with the logic contained within the lines of code but with the gaps in between. It made sense for a programmer to put a hard cap on Mario’s forward speed, but who could have foreseen that leaving his reverse speed uncapped could lead to all sorts of clever tricks?

If speedrunning is a celebration of human endurance and skill, tool-assisted play is a celebration of human curiosity and understanding. And though they might feel distant, both share a common ancestor in the question “how can I do it better?” For Scott though, this obsession to understand Super Mario 64 comes from a simple, almost childlike place: “I loved Super Mario 64, and I never wanted it to end. It wasn’t until I was able to play it on my computer using an emulator that the ceiling of what I could do and test became infinite.”

Perhaps Shigeru Miyamoto put it best when he said, “What if everything you see is more than what you see? The person next to you is a warrior and the space that appears empty is a secret door to another world? What if something appears that shouldn’t? You either dismiss it, or you accept that there is much more to the world than you think. Perhaps it really is a doorway, and if you choose to go inside, you’ll find many unexpected things.”

This article was made possible by your funding via the RPS Supporter Program. Thank you!


  1. Urthman says:

    The video behind your “that’s because it is” link is fascinating. He explains everything so well, and is clearly having a great time blowing your mind.

    link to

    I especially love the bit, which feels like something out of a science fiction novel like Tau Zero, where he essentially says, Unfortunately we can’t just teleport to the mirror galaxy 27 billion light years away, because the intermediate stutter steps between the galaxies would kill us. But we can step beyond the mirror galaxy all the way to the next mirror galaxy. Four times. Four galaxies for each of the dozen-meter hops we want to take in our world, making sure to arrange our path so that the final set of four-galaxy jumps lands us back in our own galaxy.

    (Also, the planets in the mirror galaxies have floors, but no walls, objects, or creatures. And if you open your eyes, you die.)

    • April March says:

      I randomly saw one of his videos yesterday, and I agree – he’s just so nice to people who are antagonizing him, and he explains what he’s done in an understandable way without ever coming across as smug. We ought to cherish him.

  2. Eschwen says:

    As I understand it, there’s a lot of cross-polination between the tool-assisted groups and the pure groups. Watching AGDQ this year, it was mentioned a few times that certain glitches or techniques used by games were uncovered by the tool-assisted teams, which then allowed the pure guys to improve their times or approaches to certain parts of games.

    For example, I believe it was mentioned during the last speedrun of Final Fantasy 4 that the frame on which you exit the main menu becomes the seed that determines monster encounters, which was discovered by some tool-assisted runners. This is now used in combination with step charts to plot optimal minimal-encounter routes through the game for pure speedrunning. So it would be pretty silly for people who enjoy pure speedrunning to scoff at the tool-assisted approach, as both are integral to enjoyment we get from the end result!

  3. KDR_11k says:

    Yeah, TASes often get dismissed far too easily, people think that because the tools remove the reflex challenge it’s easy to make a TAS. With great power come great expectations and the level of perfection that’s expected of a TAS these days is extremely high. You have to use every last frame saving trick that’s known and often even ones that aren’t. RNGs must be manipulated (old consoles don’t have a proper source of randomness and thus tend to seed their RNGs with controller inputs), lag frames avoided and of course it goes without saying that every corner must be taken perfectly.

    Oh and after all that? The goal of a TAS is to entertain, if it’s judged to be boring it still gets rejected.

    It takes several months to do a TAS of a game like Mega Man. Often a source of imperfection in TASes is that new techniques get discovered while the run is already months in development and they can’t be integrated without desyncing.

    BTW, while it seems that speedrunners will take any version (usually JP for shorter texts) and configuration of a game to make it faster a TAS must use the US version (if available, exceptions only when other versions allow major new tricks), run on the highest difficulty available and start with no data saved on the cartridge. Exceptions to the last part are only for explicit NG+ runs and often those NG+ saves are generated by another TAS. Of course it’s important to prove that the run does nothing that can’t be done on a real console.

  4. snoof378 says:

    Thank you, Steven, for a really interesting and well-written article. I enjoyed reading about how these things are discovered and I am in awe of what Scott and co. are able to achieve within the technical limitations of the unaltered game. They’ve created their own challenges more befitting of their knowledge and creativity than the game itself, turning it from a platformer to a puzzle of physics and mathematics – awesome!

  5. Arglebargle says:

    What really did my head in was discovering that the Mario games were originally envisioned and designed to star Popeye, til some late legal IP crap intervened.

    Never been able to look at it the same since.

  6. guygodbois00 says:

    Spider charts. Because nobody likes charts and even less the arachnophobia!?

  7. DevilishEggs says:

    I’ll never make fun of console gaming ever again.

  8. Wowbagger says:

    Dustforce is another game where TAS is in evidence, it’s strangely hypnotic to see someone working on a run in that way.

  9. April March says:

    My own thoughts echo this: link to

  10. Johnny Go-Time says:

    Fantastic article! I thought I had zero interest in the topic, but this was great.