This is a glitch known as wall cling storage, often referred to by speedrunners as 'wcs'. It's used less frequently by human runners due to the difficulty of getting the wcs state, but TAS can use it quite extensively, as it can get it by frame perfect wiggling against any wall. The wcs state has a lot of subtleties and tradeoffs, but it's particularly well-suited to staying off the ground, since not only can you dash off the invisible wall repeatedly, you can jump off the invisible wall as well (though this loses the state and you have to wiggle against a wall again to get it back.)

There are a bunch of different TASing frameworks, ranging from generic ones for various hardware platforms, to custom modded tooling injected into specific games. Some of them have a workflow that's more like editing a script file offline before relaunching, but the more advanced ones have high quality savestate support so you can easily iterate live. libTAS is a generic framework for games on Linux, though how well it works varies a lot from game to game, even when they have Linux builds.

@@jarlyk Yeah. I was mostly thinking about Hollow Knight, given that it would be painful to make a TAS so long without save states and having to check everything if it was offline scripted. Though some of the games may have even longer speeedrun TASes, but I just started wondering about it after watching your Happy Couple with two characters. I still admire that you have the patience to do all that...

On latest patch, the double spike is actually not too hard. It's regularly performed by human runners as part of almost all speedruns. It's just a matter of getting the timing down. When you see the background aspids are starting to spawn in, jump to the platform and then jump and hit the spike with the nail. It takes a little practice, but it's not frame perfect or anything.

That said, I'll caveat the above by saying that double spike is actually very tight on patch 1221, so if you're trying on that patch, don't be surprised if it seems very hard. Skilled runners can still get it pretty often, though.

@@jarlyk that's nuts i've been playing this game for 120 hours and never knew you could do that, that's dope

I actually did play around with this concept (possibly including airwalk, since technically the knight is grounded during airwalk.) The main problem is that you need to fight enemies a lot in this challenge, which gets really boring without jumping, since you're just walking back and forth and slashing, manipulating rng to try to get the enemy to jump where applicable. It's even worse with flying enemies in arenas, as you need to try to lure them close to the floor, which is slow. It's interesting/challenging from a routing perspective, but the actual gameplay/movement felt really dull.

@@jarlyk makes sense

The TAS is using a trick known as wall cling storage where wiggling against a wall with precise timing fools the game into thinking the knight is still on a wall even while midair. It's possible to dash off this invisible wall without losing the wall cling state, allowing for repeated midair dashes. It's also possible to jump off this invisible wall, though that loses the wall cling state.

It's only possible with major glitches due to a few rocks being locked behind spending geo. Notably, the lantern-locked rocks between crossroads and cpeak (behind toll gate), and the rock behind the toll elevator in crossroads. It would basically be this run, but dodging all the geo instead of picking it up, plus also adding in all the regular TE objectives. Could be interesting, but would also be obnoxiously long. An nmg version is also possible if you just omit the rocks that aren't reachable, but that's even longer. I'm not sure if it would really be all that fun to watch, since the dodging gimmick would get pretty old if it's just doing it all the time.

@@jarlyk makes sense

That's not actually a ground touch, as the knight is jumping off the invisible wall cling storage wall. There are actually several places in the TAS where the knight does this, getting extremely close to the floor, then wall jumping off an invisible wall just before landing. Note that when the knight does this, they lose the wcs state (so they can't dash midair off the wall anymore), so there are some tradeoffs and you'll often see the knight doing funky movement to jump off the wall near the floor and get up to another wall somewhere above to wiggle against and get wcs back. In cases like this though, the knight is near the exit transition and can just dash out of the wall jump.

I've always loved the concept of multiple embodiment; there's a character in Peter F Hamilton's Void Trilogy who is a single person with multiple bodies. It was also the main gimmick of the pretty good TV show Sense8 (though their linkage was a bit more variable in intensity.) Definitely an interesting area to explore.

@@jarlyk I came up with that idea randomly, possibly when thinking about bilocation. I even came up with explanation why one character has two bodies, but I don't remember which concept I dubbed "final". I like to change my ideas if I think different outcome (or explanation) is better.

TAS stands for tool-assisted speedrun, which is using special tools to play the game at a frame-by-frame level with the ability to set save states and try different options, exploring a multiverse of possible gameplay timelines and thus producing superhuman gameplay.

@@jarlyk aahh Cool, makes more sense now tbh

@@jarlyk aahh Cool, makes more sense now tbh

Lantern is hacked in so that viewers can see movement in the dark room sections. Darkness has zero impact on the TAS and the route doesn't use anything that would require lantern, so it has no gameplay impact.