Pause scene?!?

Hey there, I have a little big question.

I am a big noob so I need some help with it.

In my first scene I have the main menu.
When I press the Start Button, it destroys this scene and
loads an other scene, the ingame scene.

So now I want the following things to happen:

  • When I pres ESC the ingame scene should be paused
    (maybe with “Time.timeScale = 0;”).
  • The main menu scene should be loaded. The ingame Scene should not be destroyed.
  • When I press Escape again the main menu scene should be destroyed,
    it should go back to the ingame scene and the Game should be unpaused
    (“Time.timeScale = 1;”).

Right now, this is my (uncomplete) code:
using UnityEngine;
using System.Collections;
using UnityEngine.SceneManagement;

public class ButtonManagerIngame : MonoBehaviour {
	bool Pause = false;

	// Use this for initialization
	void Start () {
	// Update is called once per frame
	void Update () {
	public void PausiereSpiel(string PauseGameLevel, string newGameLevel)
		if (Input.GetKeyDown ("escape")) {
             if(Pause == true){
                 Time.timeScale = 1.0f;

                 Pause = false;
             } else {
                 Time.timeScale = 0.0f;
                 Pause = true;

Anyway I get compiler errors, but I don’t think it works this way…
Can anyone help me?

The Reason why I want a scene and not a canvas is, that I am not
so good in Unity and I already have a finished Main menu scene I want to use for now.

You can just use SceneManager.LoadScene (newGameLevel, LoadSceneMode.Additive); This adds the scene to the current scene. Using your code it would go something like this;
public GameObject PauseSceneRoot;

     void Start ()
                       SceneManager.LoadScene ("PauseSceneName", LoadSceneMode.Additive);

    PauseSceneRoot = GameObject.FindWithTag ("PauseMenu") //Have all your pause scene objects, inside one object with the tag "PauseMenu" or this won't work

      void Update ()
              if (Input.GetKeyDown ("escape"))
                        Pause = !Pause;
              Time.timeScale = (Paused)? 1.00f : 0.00f; //If your time scale isn't working, change Paused to !Paused

Let me know how that works.