anchor.diff:      wallsCollision.collider2 = world.collider;
       wallsCollision.onCollision.listen(bounce);
       wallsCollision.onCollision.listen((event) {
  -      if (event.delta.x != 0.0) {
  +      var side = event.delta.x;
  +      if (side != 0.0) {
  +        if (side > 0) {
  +          score2++;
  +          counter2.text = score2.toString();
  +        }
  +        else {
  +          score1++;
  +          counter1.text = score1.toString();
  +        }
  +        message.runAction(new FadeIn(1));
           ballbody.position.setValues(400.0, 200.0);
           ballbody.speed.setValues(0.0, 0.0);
         }
  
positive.code:     });
  
      var paddle2wallCollision = new StaticBodyOutOfBoundsCollisionCheck()
  
        ..collider1 = body2.collider
        ..collider2 = world.collider;
  
  
negative.code: 
    loader.load().last.then((p) {
      game.scene.onFrame.listen(world.update);
  
      var score1 = 0;
      var score2 = 0;
  
      var message = new Label('Press space to start')
            ..addTo(game.scene)
            ..align = 'center'
            ..position = new Vector2(400.0, 40.0);
  
      var counter1 = new Label(score1.toString())
        ..addTo(game.scene)
        ..align = 'center'
        ..position = new Vector2(20.0, 40.0);
  
      var counter2 = new Label(score1.toString())
        ..addTo(game.scene)
        ..align = 'center'
        ..position = new Vector2(780.0, 40.0);
  
      var controller1 = new ArcadeKeyboardController(game.keyboard)
        ..keyUp = Keys.A
  