iI think i've seen a mechanic roughly like this before ( https://managore.itch.io/windowframe ), but not with physics, so the feel is totally different. and the little Square Facts are a super charming touch. well done!
if you expand on this later... i think with how much dexterity the window resizing already takes, i'd have eschewed the jump button. it feels redundant and i end up feeling like i'm juggling a little too much
got it in 99 deaths