Fun slide puzzler! First time playing, I enjoyed the visuals and music as well as the little bit of story there was. I forgot to take a picture of the end screen, but it was about 35+ minutes and I was on the Hall of Eternity for the longest.
There was a lack of SFX, like a puzzle complete jingle, falling/respawn, breaking an obstacle, etc. As said by others the book text could be better. For a couple of the larger puzzles you didn't include ample terrain to walk around and see the whole thing, which isn't too great. Might be able to use a binoculars mechanic or something to see the entirety.
Think that's about it, game's looking really good keep it up.