Such a beautiful game! The idea is pretty unique, and the gameplay is satisfying. I think I got what runes do after a couple of loops, but maybe it would be also fine to explain them from the very beginning :) At some point the music stopped (and I liked it so much!), and I also felt that it became easier to deal with the enemies after several loops, as runes made me too powerful :) Maybe the difficulty could be increased a bit!
Great work :)