R.U.B.E stands for Really Useful Box2D Editor. This editor allows you to graphically manipulate a Box2D world and save it to a file. You can then load the saved file in your game/app and run the world. R.U.B.E can create any physics scene that Box2D itself can, with the exception that some joint types are currently not supported (gear, pulley). The main advantage of an editor like this is the speed and ease of development gained by being able to place items visually. Being able to tweak values and quickly see the results improves turnaround time when fine tuning physical behaviors. When the editing of scenes is quick and easy, more time and incentive exists for exploring different ideas, making more interesting content (or simply more of it), and creating a quality game/app that doesn't cut corners.