phun

I recently came across a game called phun.
http://www.phunland.com/wiki/Home
It is a physics simulator that lets you draw objects that interact with the enviroment.
I found myself playing it for an hour building tanks and catapults to knock down brickwalls
There are many youtube videos of it if you just want to see it:
http://www.youtube.com/watch?v=i-QlPEhLp1k
Dead Coaster:http://www.youtube.com/watch?v=AQyL9VBeq8w