The rooms here are four-dimensional. You can walk in three of the dimensions: x and y, and z is up. The fourth, w, you can only see: turn your sight and one of the walking directions swings away, replaced by w, and the world rearranges into the slice you couldn't see before. The two ways along w are ana and kata, Charles Howard Hinton's names for them.
You can't step in w, but you can hook along anything you can see. The hook catches the first thing in its way. An anchor pulls you to it, and a crate comes to you. That is how you get through the fourth dimension, and how you bring things through it.
Arrows walk · Space then an arrow hooks · V turns your sight · Q E walk the camera round · Z undo · R restart. The slices either side of the one you're in show faintly, warm on one side and cool on the other.
Every room is built at random and kept only if an exhaustive search finds a way through that hooks along w, and finds none without it. Each one has a link of its own (⤴): the room is written into the link itself, so it opens the same room for anyone, for good.