ClickThroughMenu.cs

using UnityEngine;
using System.Collections;

public class ClickThroughMenu : MonoBehaviour {
	public Texture backgroundTexture;
	public int nextScene;
	// Use this for initialization
	void Start () {
	
	}
	void OnGUI(){
		GUI.DrawTexture (new Rect(0,0,Screen.width,Screen.height), backgroundTexture);
	}
	void Update () {
		if(Input.GetMouseButtonDown(0)){
			Application.LoadLevel (nextScene);
		}
	}
}