Bold colors, hard shadows and cute, little ghost as a contrast - this all together makes a great overall look - well done! The music tracks are also great (even if they are taken from a library, the right choice matters).
Oh, and let me share a screenshot ;-) Before starting the game, I was reading your advice "Stay away from the corners!" and thought "Corners?! What's wrong with the corners?!" - 1 minute later: "Oh, now I know..." :-D
