A free physics sandbox game (source files)
thepowdertoy_source-97.0.352-1-source
The Powder Toy is a free physics sandbox game,which simulates air pressure and velocity, heat, gravity and a countless number of interactions between different substances! The game provides you with various building materials, liquids, gases and electronic components which can be used to construct complex machines,guns, bombs, realistic terrains and almost anything else.