private void Awake()
 {
     if (Instance == null)
     {
         Instance = this;
     }
 }
    // Use this for initialization
    void Start()
    {
        if (GameObject.Find("Load Game Controller") != null)
        {
            gameGontroller   = GameObject.Find("Load Game Controller").GetComponent <LoadGameController>();
            powerUpContainer = GameObject.Find("Power Up Container");
            currentPowerUps  = gameGontroller.saveData.powerUps;
        }
        foreach (PowerUp power in Enum.GetValues(typeof(PowerUp)))
        {
            allPowerups.Add(power);
        }
        List <PowerUp> possibleChoices = allPowerups;

        possibleChoices.RemoveAll(power => currentPowerUps.Contains(power));

        System.Random random = new System.Random();
        for (int i = 0; i < numberOfPowerChoices; i++)
        {
            int index = random.Next(0, possibleChoices.Count);
            powerUpChoices.Add(possibleChoices[index]);
            possibleChoices.RemoveAt(index);
        }
        populatePowerUpUIElements();
    }