Great game in almost all aspects and very cool main mechanic. I didn't like the boss fight though. it was so hard i ended up cheesing it by getting behind the boss and spamming attack until he died, and you shouldn't lose all the hearts when you enter the boss fight was painful. I really liked the visual style but maybe the bloom was a bit too much(?). Anyway, cool game.
This is the cannon that gets you soft locked, at this point you can only die trying direct its shurikens to you.