You're inside a four-dimensional room, looking out from behind your own eyes at a three-dimensional slice of it. Turn your sight and the slice swings through the fourth dimension, w; its two ways are ana and kata, Charles Howard Hinton's names for them.
Two lanes. In Anakata's rooms w is a direction you can see but not walk: you cross it with the hook, fired along whatever axis you look straight down. In Anabasis's rooms w is a second down: you fall kata for free, and only a ramp takes you ana. The strip at the left shows the slices of w where you stand, and the cell ahead.
WASD or arrows walk · click to look with the mouse, click again (or Space) to hook · V turns your sight · Z undo · R restart · L levels · N a new room. On a phone: the stick at the bottom left walks, and a drag anywhere else looks.
w is across: you see it by turning your sight, and cross it with the hook.
w is down too: you fall kata for free, and only a ramp takes you ana.
The levels and rooms are the two games' own, the same rooms and the same pars; today's rooms are theirs too. Every made room has a link of its own (⤴).