Completed the first world, half of the second world, and 7 test levels. Didn't finish the "Checkpoint" level in the test world.
It's a great puzzle game. Most of the levels (that I played) felt good, and main world progression is very smooth and enjoyable. Long Sleeve Fairy has an interesting gimmick, though not all test level utilized her fully.
I don't have much to add that hasn't been said already. Progression (main world) felt great, art is good and music is chill and enjoyable.
Feels odd to read that it's a pre-alpha since there's already so much content and polish in it.