GameController

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class GameManager : MonoBehaviour {

    public static GameManager GM;

    public GameObject player;
    public float lowerLimit = -20f;

    public GameObject HUDHistoria;
    public int coins = 0;
    public Text coinsText;
    public Text argumento;

    public GameObject HUD;
    public GameObject deadMenu;

    public Text FinalCoins;

    // Use this for initialization
    void Awake ()
    {
        if (GM == null)
        {
            GM = gameObject.GetComponent<GameManager> ();
        }
    }

    // Update is called once per frame
    void Update ()
    {
        if(player.transform.position.y <= lowerLimit)
        {
            player.GetComponent<PlayerController> ().PlayerDead ();
        }
    }

    public void PickupCoin ()
    {
        coins++;
        coinsText.text = coins.ToString ();

        if (coins == 2)
        {
            HUDHistoria.SetActive (true);
            argumento.text = "Texto de prueba";
        }

        if (coins == 8)
        {
            HUDHistoria.SetActive (true);
            argumento.text = "Texto a probar";
        }

    }

    public void EndGame ()
    {
        HUD.SetActive (false);

        FinalCoins.text = coins.ToString ();

        deadMenu.SetActive (true);
    }

    public void Retry()
    {
        SceneManager.LoadScene (SceneManager.GetActiveScene ().buildIndex);
    }

    public void MainMenu()
    {
        SceneManager.LoadScene("MainMenu");
    }
}