Basic delegate "observers"

    public delegate void StartSimulation();
    class EventManager
    {
        public static event StartSimulation startSimulationEvent;
        public static event StartSimulation startSimulation2Event;
        public static event StartSimulation startSimulation3Event;

        public static void OnStartSimulationEvent()
        {
            Console.WriteLine("Called start!!\n");
            if (startSimulationEvent != null)
                startSimulationEvent();

        }

        public static void OnStartSimulation2Event()
        {
            Console.WriteLine("Called start2 on root\n");
            if (startSimulation2Event != null)
                startSimulation2Event();
        }

    }

    class VisitedClass
    {
        public void SubscribeEvent()
        {
            EventManager.startSimulationEvent += SayHello;
            Console.WriteLine("Subscribed!\n");
        }

        void SayHello()
        {
            Console.WriteLine("Hello I have been visited!\n");
        }

        public void UnsubscribeEvent()
        {
            EventManager.startSimulationEvent -= SayHello;
            Console.WriteLine("Unsubscribed!\n");
        }
    }


    class Program
    {
        static void Main(string[] args)
        {

            VisitedClass visitedClass = new VisitedClass();
            visitedClass.SubscribeEvent();

            EventManager.OnStartSimulationEvent();

            visitedClass.UnsubscribeEvent();

            EventManager.OnStartSimulationEvent();

            Console.Read();

        }
    }