Getting a script to run without attaching it to a GameObject

I was wondering if there was a way to run a Manager / Singleton class when my game starts without attaching it to any gameObject. I need this class to hold references to my current camera and other such objects which I'd like to access from a variety of different scenarios.

This is possible since Unity 5 or so, using [RuntimeInitializeOnLoadMethod]

See: Unity - Scripting API: RuntimeInitializeOnLoadMethodAttribute

You need at least one script attached to a gameobject somwhere in your scene.

However you can use that script's Start() function as a hook from which to instantiate any number of your own classes which themselves aren't attached to a GameObject.

If you're going to create new instances like this, make sure that they don't inherit from MonoBehaviour, since the way that MonoBehaviour works makes some assumptions that it is attached to a GameObject.

So the rule for creating instances of scripts at runtime are:

  • For MonoBehaviours, always use:


  • For non-MonoBehaviours, always use:

    new MyScript();

In summary, you can have scripts running which aren't attached to GameObjects, but you can't get scripts running in the first place without at least one attached to a GameObject, to "kick things off".

IN addition you can have a singleton class that is not a monobehavior, that has links to game object in your scene. You can Call : AppState.Instance().goGame=this.gameObject;

and can be called from within empty game object script.

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class AppState  {

	public static AppState _instance = null;

	//holder for reference
	public GameObject goGame;

	public AppState() {

		Debug.Log("constructor ");



	/* singleton */
	public static AppState Instance() { 
		if (_instance==null)
			_instance=new AppState() ;

		return _instance;


Make your class extend UnityEngine.ScriptableObject, then use the ScriptableObject.Awake() function to do what you want

Best Solution : Unity - Manual: Running Editor Script Code on Launch