This is one of my favourite games so far! The mechanic was great and I liked how you executed the idea. I would maybe change the monsters into statues, that you can possess. Or you could make the monsters agressive, when you don't possess them, so that you have to get rid of them, after you finished. Anyway I loved the art style. To me, the game as the charm of an old zelda game and I really enjoyed playing it.
A very awesome game and really good work!