private void ContinueGameClick(object sender, RoutedEventArgs e)
 {
     if (File.Exists(SAVE_FILE_NAME))
     {
         GamePage gamePage = new GamePage();
         this.NavigationService.Navigate(gamePage);
         gamePage.LoadGame();
     }
     else
     {
         MessageBox.Show("Save not available. Click \"Play\" to start new game.");
     }
 }
 private void PlayClick(object sender, RoutedEventArgs e)
 {
     GamePage gamePage = new GamePage();
     gamePage.runTimer();
     this.NavigationService.Navigate(gamePage);
 }