Falling sand automaton on FPGA

http://people.ece.cornell.edu/....land/courses/ece5760
The Pyro Sand Game is itself only one of many variations of similar falling sand games. It includes 17 different drawable particle types, most of which can be categorized as either an immobile wall-like particle (such as wall, plant, or wax) that ignores both gravity and other forces, or a mobile sand-like particle (such as sand, water, or salt) that does experience a gravity force and can be pushed by other particles.