/// <summary>
        /// Event handler for when the Play Game menu entry is selected.
        /// </summary>
        void PlayGameMenuEntrySelected(object sender, PlayerIndexEventArgs e)
        {
            switch (lesson)
            {
            case 1:
            {
                GameplayScreen l1       = new GameplayScreen(1);
                float          minScore = 150;
                l1.AfterLoadContent = delegate()
                {
                    PlayerManager pm = Costam.PlayerManager;
                    Player        pl = Costam.PlayerManager.players.Values.ElementAt(0);
                    pl.ShootingEnabled = false;
                    l1.objectManager.InitDiamondSequences();
                    l1.objectManager.VirusGenerator.Enabled = false;
                    Trigger lessonOneTrigger = new Trigger();
                    lessonOneTrigger.Condition = delegate()
                    {
                        return(pl.score >= minScore);
                    };

                    lessonOneTrigger.Action = delegate()
                    {
                        lessonOneTrigger.Enabled = false;

                        ScreenManager.AddScreen(new GameOverScreen(pl.score, "Excellent!", false, 1), ControllingPlayer);
                    };

                    Costam.TriggerManager.AddTrigger(lessonOneTrigger);
                };


                LoadingScreen.Load(ScreenManager, true, e.PlayerIndex, l1);
            }
            break;

            case 2:
            {
                GameplayScreen l2       = new GameplayScreen(2);
                float          minScore = 150;
                l2.AfterLoadContent = delegate()
                {
                    PlayerManager pm = Costam.PlayerManager;
                    Player        pl = Costam.PlayerManager.players.Values.ElementAt(0);
                    pl.ShootingEnabled = false;

                    l2.objectManager.InitDiamondSequences();
                    l2.objectManager.InitBloodSequences();
                    l2.objectManager.VirusGenerator.Enabled = false;
                    Trigger lessonTwoTrigger = new Trigger();
                    lessonTwoTrigger.Condition = delegate()
                    {
                        return((pl.score >= minScore) && pl.CollisionWithRedBLoodCellHappened);
                    };

                    lessonTwoTrigger.Action = delegate()
                    {
                        lessonTwoTrigger.Enabled = false;

                        ScreenManager.AddScreen(new GameOverScreen(pl.score, "Congratulations!", false, 2), ControllingPlayer);
                    };

                    Costam.TriggerManager.AddTrigger(lessonTwoTrigger);
                };


                LoadingScreen.Load(ScreenManager, true, e.PlayerIndex, l2);
            }
            break;

            case 3:
            {
                GameplayScreen l3          = new GameplayScreen(3);
                float          killViruses = 10;
                l3.AfterLoadContent = delegate()
                {
                    PlayerManager pm = Costam.PlayerManager;
                    Player        pl = Costam.PlayerManager.players.Values.ElementAt(0);
                    pl.ShootingEnabled = true;

                    l3.objectManager.InitDiamondSequences();
                    l3.objectManager.InitBloodSequences();
                    l3.objectManager.VirusGenerator.Enabled = true;
                    Trigger lessonThreeTrigger = new Trigger();
                    lessonThreeTrigger.Condition = delegate()
                    {
                        return(Costam.ColisionManager.virusesKilled >= killViruses);
                    };
                    lessonThreeTrigger.Action = delegate()
                    {
                        lessonThreeTrigger.Enabled = false;

                        ScreenManager.AddScreen(new GameOverScreen(pl.score, "Great! You have finished all lessons", false, 3), ControllingPlayer);
                    };

                    Costam.TriggerManager.AddTrigger(lessonThreeTrigger);
                };


                LoadingScreen.Load(ScreenManager, true, e.PlayerIndex, l3);
            }
            break;
            }
        }