/** Should only be called from Bomb.Blow() */
        public void BlowBomb(Bomb bomb)
        {
            int cx = bomb.GetCx();
            int cy = bomb.GetCy();

            bomb.RemoveFromField();
            SetFlame(bomb, cx, cy);

            bomb.player.OnBombBlown(bomb);

            bool up = true, down = true, left = true, right = true;
            int radius = bomb.GetRadius();

            for (int i = 1; i <= radius && (up || down || left || right); ++i)
            {
                left = left && SetFlame(bomb, cx - i, cy);
                up = up && SetFlame(bomb, cx, cy - i);
                down = down && SetFlame(bomb, cx, cy + i);
                right = right && SetFlame(bomb, cx + i, cy);
            }
        }