i think the ultrakill secret levels are canon and here’s why (and how):
i think the secret levels (minor exception for 0-S) act as additional punishment for damned souls (husks) that try to escape. they’re difficult to find (hence being *secret* levels), and, based on evidence from books we can find, especially the new ones in Fraud, we can infer that the husks in Hell are actually able to find them, at least sometimes. the Big Johninator book in 7-1 could be brushed off as being non-canon because it was hidden behind a jokey secret boss, but the Ferrymen book in 8-3 makes it feel a lot more like it can be canon.
here’s my thoughts on how the individual secret levels are punishments:
0-S: not directly a punishment, per se, but rather a method of security. when a husk tries to escape Hell and get back to Earth proper, Hell sends them to 0-S in an attempt to scare them into going back into Hell. if simply scaring them doesn’t work, Something Wicked kills them, and, as explained in a dev stream, husks dying is permanent (with the exception of Prime Souls)
1-S: Limbo seems to be a land of boredom, with nothing to do. 1-S is something to do, but it’s the ONLY something to do. desperate souls find 1-S, are excited by the puzzles, but then, after completing them, they realize there truly is nothing left to do. they’ve already solved the puzzles, making those boring to redo.
2-S: i think Mirage is like Nosk from Hollow Knight, and the Mirror Reaper’s V1 marionette — Hell Itself reads the mind of whoever ends up in 2-S to create a fake entity of “their type”, and Mirage looks like V1 in a schoolgirl outfit because, being a machine, V1 wouldn’t be sexually attracted to anything, so Hell just takes V1 themself and adds the schoolgirl outfit as a sort of “least common denominator”. then, once Hell made someone you’re attracted to, it puts you both in a situation where you magically get your dream person interested in a date, and then rips it from you right before you get to “the good part”. this is also, of course, evidenced by Mirage’s name.
4-S: really hard platformer with a very obvious goal for completionists. husks in greed try to get the completion, and get a super mediocre reward. i have no other thoughts on this one.
5-S: probably my best one. it’s the secret level for Wrath, holding hatred for other people, and the ending? it shows that you and everyone else caught Size 1 at best, except for two people, who caught Size 2. it’s designed to make you angry (wrathful) towards the two who caught Size 2, and then drive you insane trying to find it yourself. the fact that the only two who’ve caught it are the devs is just because it’s a work of fiction
7-S: gives you an opportunity for violence, then forces you to go through the tedious work of cleaning it up. pretty self explanatory, i think
(as of making this post, 8-S is not out yet)
