var paused: boolean;
    function OnGUI() {
        // Show a message if the game is paused.
        if (paused) {
            GUI.Label(new Rect(100, 100, 50, 30), "Game paused");
        }
    }
    function OnApplicationFocus(focusStatus: boolean) {
        paused = focusStatus;
    }

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public bool paused;
    void OnGUI() {
        if (paused)
            GUI.Label(new Rect(100, 100, 50, 30), "Game paused");
        
    }
    void OnApplicationFocus(bool focusStatus) {
        paused = focusStatus;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public paused as bool

    def OnGUI():
        if paused:
            GUI.Label(Rect(100, 100, 50, 30), 'Game paused')

    def OnApplicationFocus(focusStatus as bool):
        paused = focusStatus