I would like something where, say your "hero", lets say it is a space ship, is controlled by the mouse, with a drag. I want so that when it collides with another object, it will push that object. The best example I could find was this: http://homokaasu.org/gasgames/game.gas?20 I'm more looking for line to line detection, not circle. But the main this here is the non-conservation of energy. The object the user is "pushing" doesn't bounce back, it merely pushes the other object. Any thoughts?