We're using Box2dLights for lighting- haven't done much with it yet, but hoping to have a few interesting light sources and elements in the game to add some ambience to the space theme. Basically we take a tile map built with Tiled and convert tiles into Box2d squares to build the world. Nothing else uses the physics as for a platformer I find physics engines a bit strange, so we wrote the physics ourselves (fairly basic platforming logic, translate Y, check for collisions adjust DY accordingly, then do some for X access). We put a few special cases in to handle wall jumping.