Hi. I'm Lexi. I speedrun, TAS, and mod this game. You might have noticed the recent RTA world records in the Portal category feature some brand new tech never seen before outside of I and @Masterjun's tool assisted speedruns. I'd like to talk about how they work and how to perform them yourself, and introduce for discussion a speedrunning mod I've made for the game.

To start, the physics. If you've ever watched a pannenkoek video, you probably know that games perform physics updates in steps. The more steps done each second, the more incremental the changes in each step, and the less likely it is for these incremental changes to somehow clip the player through a wall. Well, Mari0 has no such incremental step system. Or rather, the physics is stepped only once every frame. This means that, the lower the FPS the game runs at, the easier it is to clip through walls and floors, because there will be less physics updates each second, and thus Mario will move a larger amount on each update to compensate. (Don't worry, this is about as deep into the technical details that this post will go.)

Now, Maurice knew about this while he was creating the game, and thus he enforces a minimum frame rate of 1/0.01666667, which is roughly (microscopically under) 60FPS. If your computer can't keep up with this minimum then the game will just run slow so that Mario doesn't clip through the floor and die just from jumping too high. While he coded in this minimum frame rate, he unfortunately did not code in an option to set a maximum frame rate which is necessary to perform these new clips. Though, I'm getting a bit ahead of myself- first I should talk about what these new clips are and how to perform them.

The clip in 1-1 is pretty much as simple as it looks, though it's highly dependent on frame rate. In fact, if you play on the lowest possible frame rate, then the only way to quickly get the clip is to fire the wall portal and hold Run+Left after performing six loops (so, entering the portal on the floor six times). Different frame rates will allow you to clip at different times and in different ways (i.e. in my PB, my game was apparently not running at a perfect minimum, so I was able to clip without holding anything (or maybe I was holding Right, I don't remember)).

The first clip in 1-4 was pioneered by @WilliamFrog and has different setups depending on your frame rate. William's setup of performing a full height jump into the wall then hanging back (only after trying to clip just by falling from the upper platform) works best for him on his ~60 FPS limit, though for my roughly minimum FPS limit I use a different setup he created which involves doing a full jump off the cube and then hanging left. Either way, you want the majority (but not all) of Mario's body to be over the tile to the right of the floor portal as you clip, and you want to be holding left.

The emancipation grill clip in 1-4 is a bit older and simpler in that it's not so framerate dependent, but harder in that it's a frame perfect trick. My simple setup for it is to drop the cube a little before the kill point and then lightly mash the Right key, with the goal being that I press it for just a single frame each time until the cube is past the kill point. William's setup is no setup, he's just a god gamer who can nail the frame perfect drop past the kill point consistently.

In 2-3, William goes for a strat which I think is relatively straightforward to understand just from watching it, though it's quite difficult to actually pull off. I haven't learned it yet because it's hard and it's not necessary for WR yet so I don't remember the exact timing to pull it off, I'll edit in here later.

(apparently SRC has a character limit now, see reply for the rest of this post.)

Not sure if this is known or not but discovered while TASing that hitting the cube boss the frame it lands on the ground causes it to keep its downward speed, allowing you to hit it much earlier for the subsequent hits. Not sure if RTA viable but would save quite a few seconds.