Pretty ambitious project for a game jam: very impressed with the size of the levels and the puzzle design. I think that the spirit form would benefit from "ethereal" vision of the world (maybe a post process effect). This would be both for style and to hint to the player where to go and with what objects to interact.
Discovering what the katana was used for made me laugh and cry at the same time; but it made me excited to go to ghost form each time. Definitely a fun game. I didn't finish it but this is one I plan to come back to soon.