anchor.diff:      });
   
   
  -
  +    player.speedX = 300;
       if (game.isMobile) {
   
         Button leftButton = game.add.button('flatDark23', 'L')
  
positive.code:           ..x = game.world.width - rightButton.width.toInt()
            ..y = game.world.height - 100;
  
        game.touch.onTouchBeginAndEnd(leftButton, player.goLeft, player.stopLeft);
  
        game.touch.onTouchBeginAndEnd(
            rightButton,
            player.goRight,
            player.stopRight);
  
      } else {
  
        game.keyboard.onDownAndUpKeyHandler(
            KeyCode.LEFT,
            player.goLeft,
            player.stopLeft);
  
        game.keyboard.onDownAndUpKeyHandler(
            KeyCode.RIGHT,
            player.goRight,
            player.stopRight);
  
      }
  
    }
  
    update() {
      if (!ufos.anyAlive()) {
        bulletTimer.cancel();
        killState();
  
negative.code:     score = 0;
      scoreText = game.add.text("Score: $score", size: 20);
  
      player = game.add.sprite('playerShip1_blue')
          ..x = game.world.width ~/ 2
          ..y = game.world.height - 200;
  
      bullets = new Group<Sprite>();
      for (int i = 0; i < 5; i++) {
  