Fisher Yates

    public static void Shuffle<T>(this IList<T> l)
    {
        int n = l.Count;
        for(int i = 0; i < n - 1; i++)
        {
            int j = UnityEngine.Random.Range(i, n);
            if (j == i) continue;
            T temp = l[i];
            l[i] = l[j];
            l[j] = temp;
        }
    }