fun game =) spot on with the physics- the mass, friction, inertia play very well. and the vertical scroll while building has a great feel to it. you might want to add some more collision sounds- whenever i spill a large tower i expect large crashing noises ;) and some diversity to the sounds when stacking toys might add a lot- like a soft sound when stacking dolls and a hefty sound when stacking boxes. overall: great job! =D