The code in this chapter

The code for GameManager.cs is as follows:

 using UnityEngine;
 using System.Collections;
 
 public enum GameState {
     menu,
     inGame,
     gameOver
 }
 
 public class GameManager : MonoBehaviour {
 
     public static GameManager instance;
     public GameState currentGameState = GameState.menu;
 
     public Canvas menuCanvas;
     public Canvas inGameCanvas;
     public Canvas gameOverCanvas;
 
 
     void Awake() {
         instance = this;
     }
 
     void Start() {
         currentGameState = GameState.menu;
     }
     
     //called to start the game
     public void StartGame() {
         PlayerController.instance.StartGame();
         SetGameState(GameState.inGame);
     }
     
     //called when player die
     public void GameOver() {
         SetGameState(GameState.gameOver);
     }
 
     //called when player decide to go back to the menu
     public void BackToMenu(...