private void ShufflePlatforms()
        {
            int n = Platforms.Count(); //fisher yates

            while (n > 1)
            {
                n--;
                int k     = Main.rand.Next(n + 1);
                NPC value = Platforms[k];
                Platforms[k] = Platforms[n];
                Platforms[n] = value;
            }
        }