Pretty nice little game and a great concept. I really like how there are platforms that appear only when the characters are alive and ones that appear when they are dead. I also like the pixel art and the particle effects on the circle things. There are two things I would like to point out firstly the music feels a little repetitive and would get annoying after a while. This would mainly be the problem I feel though if the game was bigger and had more levels. The second thing is that in the last level if when you are the ghost you can get stuck between the two walls making you have to refresh the page and restart the game to get out. It is just something that is a little annoying and could easily be fixed by changing the levels design a little bit or you could add a way to restart a specific level. Overall though the game was great and really enjoyed it.
That's all of my feedback, I hope it could be of some use. If you don't mind If looking at my game and giving it some feedback would be greatly appreciated (don't normally ask, but find haven't had anyone really rate or give feedback, and getting feedback is the most important thing to me).