Woo - I've fixed my scratch! Just installed it in a different directory. Now I can keep working on stuff. :D This is just a test physics app I made. I was testing how a well functioning physics engine would work and how well it would function with scratch's skippy collision system. Detecting pixel by pixel collision would require Atomic Recursion of Velocity Movement and Collision Detection - which is very possible in scratch with a BYOB like system. Although this would work perfectly it would not be very fast - as scratch does not like object movement. Also it shakes the stage when collision occurs and the engine allows offscreen movement. The ball has a shiny bloom effect aswell.