HK actually does have glitches that can give you noclip, but this TAS doesn't use any of them. In general, I find noclip movement kinda boring, as you're not interacting with geometry, just moving directly to the next transition zone. The vast majority of major glitches in this TAS come down to the principle of getting control when you're not supposed to have it; almost everything else, like duplicating rooms, follows from that. All of these glitches are well-known in the community, as well and human players execute them in their own glitched runs.

This would require some hackery, but could in theory be possible. Would be pretty difficult to implement, though. The normal multiplayer mod does allow this, but the TAS synchronization is using a different mechanism to sync flags, since a TAS can't run in multiplayer due to technical details of how it functions.

@@jarlyk Check. Would sometthing like a Minecraft TAS work better, just replayed movements made in slow motion, sped up?

The tools used for tool-assisted speedrunning allow for super-human feats that are essentially impossible for humans, usually due to some combination of being impossibly precise or requiring a great deal of luck (TAS is deterministic, so we can add inputs to reroll random events until we get the outcome we want.) As a result, it's common to personify TAS as a 'robot' player that does things no human could accomplish.

@@jarlyk oooohhhhh tham makes sm more sense now tytyty

It's hard to tell, but it's actually a wall jump that is made possible by wall cling storage

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