Roblox - Reimagining the way people come together.
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.
Lunacraft - Lunacraft focuses on Endless Creativity and Exploration elements.
SimPhy - Interactive 2D & 3D Physics simulation software
Blockland - Blockland is a non-competitive multiplayer sandbox-style construction game. It's kind of like playing with legos on the internet.
Physion - Physics Simulation Sandbox