Oooh my, very nice. Nailed the aesthetic, puzzles were appropriately hard, music fits the theme. I liked the start screen/ending connection too.
Only suggestion I can give for improvement is... more of the same ;)
And more of the same is what I want too. Overall good feedback can push me enough to finally release full version of jam's "proof of concept" :)
Let's hope this will be the one!
Thanks!