Excellent puzzler with amazing physics
What I think keeps the game fresh is that they keep throwing new pieces and different concepts into the mix. Just when you get the idea of how to use a certain piece, they add a new piece with different applications.
I also appreciate the fact that they didn't really need super-fancy graphics or movies to explain what to do and to keep you interested. There is a little sign that always gives you a hint of the purpose of a puzzle + how to accomplish the task. And the pieces all have their little charm that keeps the atmosphere fun.
Anyways, Well worth the money if you like puzzle games...