/// <summary>
        /// Play Sound Effect
        /// </summary>
        /// <param name="name">SE name.</param>
        public static void PlaySound(string name)
        {
            SoundEffect se = null;

            _ses.TryGetValue(name, out se);

            if (se == null)
            {
                se = GameContent.LoadContent <SoundEffect>("sound/" + name + ".wav");
                _ses.Add(name, se);
            }

            se.Play();
        }
        /// <summary>
        /// Changes background music.
        /// </summary>
        /// <param name="title">BGM title.</param>
        public static void PlayBGM(string title)
        {
            if (title != _currentBGM)
            {
                Song song = null;
                _bgms.TryGetValue(title, out song);

                if (song == null)
                {
                    song = GameContent.LoadContent <Song>("bgm/" + title + ".wav");
                    _bgms.Add(title, song);
                }

                _currentBGM = title;
                MediaPlayer.Play(song);
            }
        }