Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
Algodoo - Algodoo is a 2D simulator freeware product designed as a physics learning tool. It was originally created by Emil Emerfeldt as part of his master’s thesis in 2008. Read more about Algodoo.
Starbound - This action-adventure platformer throws you into a procedurally generated galaxy where you can make your mark.
SimPhy - Interactive 2D & 3D Physics simulation software
Deepworld - Deepworld is a massively-multiplayer 2D crafting adventure game.
Physion - Physics Simulation Sandbox