Thank you for playing through all 10 levels! I'm glad the difficulty felt fair.
You're right about "enclosure" — I can see how that word could be confusing. I'll take another look at it.
I like your point about new mechanics rather than another character. Pushable blocks, switches, and temporary shape changes are all interesting. The slideshow idea for the unlocked illustrations is a nice one too.
Thanks for the thoughtful feedback — it helps me think about what could come next.