public MainPage()
        {
            this.InitializeComponent();
            this.NavigationCacheMode = NavigationCacheMode.Enabled;

            game = new LightsOutGame();
            CreateGrid();
            DrawGrid();
        }
 protected override void OnNavigatedTo(NavigationEventArgs e)
 {
     if (ApplicationData.Current.LocalSettings.Values.ContainsKey("grid"))
     {
         string json = ApplicationData.Current.LocalSettings.Values["grid"] as string;
         game = JsonConvert.DeserializeObject <LightsOutGame>(json);
         DrawGrid();
     }
 }