"Crayon Physics Deluxe is a puzzle game designed by Petri Purho and released on January 7, 2009. An early version, titled Crayon Physics, won the grand prize at an independent video game festival. It features a heavy emphasis on two-dimensional physics simulations, including gravity, mass, kinetic energy and transfer of momentum. The game includes a level editor and enables its players to share and download custom content via an online service." Source: Wikipedia, "Crayon_Physics_Deluxe," available under the CC-BY-SA License.