I have spent wonderful time with this demo! My favourite segment is path to bookshelf - beside screaming babies, they were kinda mean :P In all seriousness, such various use of beam's simple mechanic was super fun and exciting.
I gave up on the part with purple key - it became too frustrating for me, but I am also not the best at platformers. :')
Backgrounds are super unique and often stunning - one ot the most satisfying moments was floating between columns in some side room. It's one example of many nice touches that make your game look polished.
I will surely give it another time in the future. Good luck in development!