Generic message-based GameEvent Class for Unity

GameEvent.cs

using UnityEngine;
using System.Collections;

public delegate void GameEventDelegate(GameEvent evt = null);

[System.Serializable]
public class GameEvent {

	public GameObject target;
	
	public GameObject instigator;

	public string message;
#if USE_PLAYMAKER
	public bool fsmEvent = false;
#endif
	public SendMessageOptions messageOptions = SendMessageOptions.DontRequireReceiver;
	public string tag;

	public bool activateTarget = false;

	public bool once = false;
	public float retriggerDelay = 0;
	[System.NonSerialized]
	public float lastTriggered = Mathf.NegativeInfinity;

	public string stringParam;
	public float floatParam;
	public bool boolParam;
	public GameObject objectParam;
	
	public bool Trigger( GameObject _instigator = null ) {
		if (once && lastTriggered > 0)
			return false;
		
		if (lastTriggered+retriggerDelay > Time.time)
			return false;
		
		if (instigator == null)
			instigator = _instigator;
		
		lastTriggered = Time.time;
		
		if (target) {
			if (activateTarget) {
#if UNITY_3_5 || UNITY_3_4
				target.SetActiveRecursively(true);
#else
				target.SetActive(true);
#endif
			}
			
#if USE_PLAYMAKER
			if (fsmEvent) {
				PlayMakerFSM fsm = target.GetComponent<PlayMakerFSM>();
				
				if (fsm == null) {
					Debug.LogError("GameEvent:Trigger: target doesn't have FSM.");
					return false;
				}
				
				if (message == "")
					message = "Trigger";
				
				fsm.SendEvent(message);
			}
			else {
#endif
				target.BroadcastMessage(message, this, messageOptions);
#if USE_PLAYMAKER
			}
#endif
		}
		
		if (tag != "") {
			GameObject[] targetList = GameObject.FindGameObjectsWithTag(tag);
			
			foreach(GameObject go in targetList) {
				if (activateTarget) {
#if UNITY_3_5 || UNITY_3_4
					go.SetActiveRecursively(true);
#else
					go.SetActive(true);
#endif
				}

				go.BroadcastMessage(message, this, messageOptions);
			}
		}

		return true;
	}
}

Add to MonoBehaviours, like this:

public class MyGO : MonoBehaviour {
    public GameEvent someEvent;

    // in a script you trigger the event like this
    public void TriggerEvent() {
        someEvent.Trigger(gameObject);
    }

    // Event handler, "MyEvent" is set as message in GameEvent
    public void MyEvent(GameEvent ev = null) {
        Debug.Log("MyEvent triggered by ", ev.instigator);
    }
}