public static Maze Generate(int w, int h)
        {
            var m = new Maze() { Map = new bool[w * 2 + 1, h * 2 + 1] };
            m.Map[m.W / 2, m.H - 1] = true;
            m.Open(new intVector2(m.W / 2, m.H - 2));
            return m;
        }

        void Open(intVector2 p)
        {
            Map[p.X, p.Y] = true;
            foreach (var d in Directions.Shuffle(rng))
            {
                var wall = p + d;
                var next = wall + d;
                if (Bounds.Contains(next.X, next.Y) && !Map[wall.X, wall.Y] && !Map[next.X, next.Y])
                {
                    Map[wall.X, wall.Y] = true;
                    Open(next);
                }
            }

        }