Making games in Scratch is an easy task, but some things are a bit complex, So, what about an super-simple Physics Extension that would make things a bit less complex, Personally I think this it would be a great time-saver but it may also make too easy so that's why I'd like to keep it very limited, only simple blocks like X/Y Velocity, Friction(Limited and Basic) Basic Collision Detection, and a few little things more. It won't be able to make super advanced things and experienced people could still make custom and better engines, It would a great extension a time saver for quick projects or beginners.