text: 
  
  function tick() {
    
    if (game.over || game.paused) return;
  
    // all items and items off of screen, start next level
    if (game.enemies.children.length < 1) {
      game.score += 1000; // clear level point bonus
      game.level++;
      game.buildNewEnemyGroup(game.numEnemyGroups++);
    }
  
    // reward for points
    if (game.score > game.rewardInterval * game.rewardLevel) {
      game.rewardLevel++;
      game.skookum.shield = true;
      game.skookum.gotoAndStop(4);
    }
  
    game.stage.update();
  }
  
  
  (function() {
  
    // initialize game
    window.game = new Game({
      fps: 60,
      startLevel: 1,
      rewardInterval: 5000, 
      rewardLevel: 1
    });
  
    // start game
    game.initialize();
  
  })();