Easiest way to pause your Unity game | TimeScale | Pause | Resume | Unity | @Unity3DSchool

PauseManager.cs

using UnityEngine;

public class PauseManager : MonoBehaviour
{
    bool isPaused = false;
    public GameObject PauseMenu;
    float timeScale;

    void Update()
    {
        if(Input.GetKeyDown(KeyCode.Escape))
        {
            if(isPaused) Resume();
            else Pause();
        }
    }

    void Pause()
    {
        isPaused = true;
        PauseMenu.SetActive(true);
        timeScale = Time.timeScale;
        Time.timeScale = 0.0f;
    }

    void Resume()
    {
        isPaused = false;
        PauseMenu.SetActive(false);
        Time.timeScale = timeScale;
    }
}

GameManager.cs

using System.Collections;
using UnityEngine;

public class GameManager : MonoBehaviour
{
    void Start()
    {
        StartCoroutine(DebugCoroutine());
    }

    void Update()
    {
        if (Time.timeScale == 0) return;
        Debug.Log("Update is running...");
    }

    void FixedUpdate()
    {
        Debug.Log("FixedUpdate is running...");
    }

    IEnumerator DebugCoroutine()
    {
        while(true)
        {
            yield return new WaitWhile(() => Time.timeScale == 0);
            yield return new WaitForEndOfFrame();
            Debug.Log("coroutine is running...");
        }
    }
}