ejemplo mas o menos

public class startTimer
{
    Timer timer;
    GameClient Session;
    int timeLeft;

    public startTimer(GameClient Session, class Function)
    {
        this.Session = Session;

        int time = 1;
        timeLeft = time * 500;

        startTimer();
    }

    public void start()
    {
        TimerCallback timerFinished = timerDone;
        timer = new Timer(timerFinished, null, 500, Timeout.Infinite);
    }

    public void timerDone(object info)
    {
        try
        {
            timeLeft -= 500;

            #region Conditions
            if (Session == null)
            { stopTimer(); return; }

            if (timeLeft > 0)
            {
                // aqui se pone la clase a ejecutar
                new Function();

                timer.Change(500, Timeout.Infinite);
                return;
            }
        }
        catch { stopTimer(); }
    }

    public int getTime()
    {
        int minutesRemaining = timeLeft / 60000;
        return minutesRemaining;
    }

    public void stopTimer()
    {
        timer.Dispose();
    }
}