The Powder Toy is a desktop version of the classic 'falling sand' physics sandbox, it simulates air pressure and velocity as well as heat !
Extremely impressed by this program! It does so much and still works so well. A bit complicated to learn, but fantastic once you get past that.
Try my games : http://neotron-games.blogspot.com
Latest version is 44.6
yeah, 10 of out 10 for 3 votes.