public GameEventManager(GameObjectManager gameObjectManager)
 {
     this.gameObjectManager = gameObjectManager;
 }
 public CreateZombies(GameObjectManager gameObjectManager)
 {
     this.isRunning         = true;
     this.gameObjectManager = gameObjectManager;
 }
 public Demo(GameObjectManager gameObjectManager, GameEventManager gameEventManager)   //constructor
 {
     this.gameObjectManager = gameObjectManager;
     this.gameEventManager  = gameEventManager;
 }