Algodoo

Algodoo, previously Phun, is an educational, entertaining and somewhat addictive piece of software for playing around in a 2D physics sandbox in a cartoon-y fashion.

Free Personal Mac OS X Windows iPad

Physion

Physion is a Physics simulation software for creating interactive physics simulations and educational experiments.

Free Windows Linux

Step

Step is an interactive physics simulator. It works like this: you place some bodies on the scene, add some forces such as gravity or springs, then click...

Free Open Source Linux

Mutilate-a-Doll 2

A highly customisable virtual stressball and physics sandbox about mutilating ragdolls in various ways using an overwhelming amount of items and other tools.

Commercial Mac OS X Windows Linux Web Kongregate