Main Menu MonoBehaviour

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class MainMenu : MonoBehaviour {
    public Button newGameButton;
    public Button loadButton;
    public Button exitGameButton;
    public string newGameSceneName;

    public GameObject loadGameMenu;

    public void Awake() {
        newGameButton.onClick.AddListener(NewGame);
        loadButton.onClick.AddListener(OpenLoadGameMenu);
        exitGameButton.onClick.AddListener(ExitGame);
    }

    public void NewGame() {
        SceneManager.LoadScene(newGameSceneName);
    }

    public void OpenLoadGameMenu() {
        loadGameMenu.SetActive(true);
    }

    public void ExitGame() {
        Debug.Log("Trying to exit game. Doesn't work in editor.");
        Application.Quit();
    }
}