It uses a physics library ("JBox2D") - I didn't do the physics calculations myself. And the debug display is really slow online - looses like 50% performance :)

Sorry, I’m not on Facebook. For the ragdoll game, you would have to use joint to connect different rigidbodys. That is possible with Box2D, but I don’t know how yet so maybe I will do something like that at some point, but for now I’m going to work on some essentials. Because, what you see doesn’t really use any of the Greenfoot libraries and thus I don’t have stuff like collision detection and similar just yet. Therefore this application can also run completely without Greenfoot, but that’s why I’m concentrating onto the „engine“ rather than the actual game.