[Drag a Ball] using your mouse [1,2,3,4, or 5] to add new balls! [D] Delete Ball [R] to Remove ALL balls [Space] Line drawing mode [Q & E] to set portals [L] Load a Scene [S] Save your Scene [B] toggle Scene Borders [Z] Engine Tuner (Gravity, etc) [H] Help (on/off) [P] Pause the simulation I've been reading a web based tutorials by a guy named Randy Gaul (http://tutsplus.com/authors/randy-gaul) on how to implement a Rigid Body Physics Engine... The upshot is... It's complex! *grin*. I have only begun to implement the basics: Supporting circles with basic Impulse resolution and overlapping object correction. No friction, rotation or torque :S And no non-circular bodies! :S