Cool game but it is still incomplete. And has some bugs too. For example, you can get an infinite amount of collectibles by going back to the level you have already cleared.
The boss doesn't seem to have a cooldown I think. I couldn't even hit him once because he just wouldn't stop attacking himself.
Also, the game basically stops the moment you die. You would have to restart the game to play it again. It does not have a replay feature yet.
Other than that it was pretty cool.