Time for action – updating the Game1 class

1. Add the following declarations to the Game1 class:

   enum GameStates {TitleScreen, Playing, WaveComplete, GameOver};
   GameStates gameState = GameStates.TitleScreen;
   
   float gameOverTimer = 0.0f;
   float gameOverDelay = 6.0f;
   
   float waveCompleteTimer = 0.0f;
   float waveCompleteDelay = 6.0f;

2. Remove the call to GoalManager.GenerateComputers() from the LoadContent() method of the Game1 class.

3. Add the checkPlayerDeath() method to the Game1 class:

   private void checkPlayerDeath()
   {
       foreach (Enemy enemy in EnemyManager.Enemies)
       {
           if (enemy.EnemyBase.IsCircleColliding(
               Player.BaseSprite.WorldCenter,
               Player.BaseSprite.CollisionRadius))
           {
               gameState = GameStates.GameOver;
           }
       }
   }

4. Replace the existing Update() method of the Game1 class with the following:

   protected override void Update(GameTime gameTime)
   {
       // Allows the game to exit
       if (GamePad.GetState(PlayerIndex.One).Buttons.Back ==
          ...