I had this same idea... except that the player and the ghosts would be 'realistic.' as in, the player is a large, round head with a wide, chesire mouth, and the ghosts were large, bulbous tumors walking on a 360 degree circumference jawless maw
I have to say this is one of the better designed games on Kongregate with some pretty nice switching between all 3 monsters, but more hazards and more forms would be nice, because as many people said it got repetitive with just #1 and #2 switching, with just a bit of #3 involved (like the levels with glass and platforming. Those were cool)
This needs a "make money invisible" button. Money is still there, but you can't see it.
That way I stop going out of my way to grab it when I don't actually need it :P