The description says that the game crashes on Firefox, but it didn’t crash once when playing on Firefox Nightly (116.0a1 (2023-06-22) as of the time of writing) on Gentoo Linux; I’ve successfully played through all of the stages and unlocked the entire gallery just now. The only thing that did happen was everything but the animated background disappearing from the iframe once, possibly related to me having scrolled down the page a fair bit, but a simple page refresh did the trick.
Awesome work and I wish the devs a great day!