code: function() {
          // clear the background
          me.game.world.addChild(new me.ColorLayer("background", "#000000", 0), 0);
          // add a few squares
          me.game.world.addChild(new game.square(200, 230, {width: 100, height: 100}), 1);
  
          // add a droptarget entity
          me.game.world.addChild(new game.droptarget(400, 200, {width: 200, height: 150}), 1);
  
          // add another droptarget entity
          me.game.world.addChild(new game.droptarget2(400, 400, {width: 200, height: 150}), 1);
      }
docs: action to perform on state change