Code in this chapter

Here is the code for GameManager.cs:

 

using UnityEngine; 
using System.Collections; 
 
public enum GameState { 
  menu, 
  inGame, 
  gameOver 
} 
 
public class GameManager : MonoBehaviour { 
 
  public static GameManager instance; 
  public GameState currentGameState = GameState.menu; 
 
 
  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() { 
    SetGameState(GameState.menu); 
  } 
 
  void SetGameState (GameState newGameState) { 
     
    if (newGameState ==...