Simple game design really is a beautiful thing. You find a mechanic that is fun to noodle with (like the slippery control logic), throw in a hook to get people

Simple game design really is a beautiful thing. You find a mechanic that is fun to noodle with (like the slippery control logic), throw in a hook to get people ("oh look! a green square!") and then you can refine and refactor into a billion different permutations. My favorite part about this was how the red square would get faster in bursts. It was like the baddie was getting increasingly exasperated about his whole damn situation.