This is really nicly done ! I would love to learn more on the music and sound part. Can we use your music software tracker? Do you have a music player for Arduino?
I ask this because we (TEAM a.r.g.) are creating 8-bit games for the Gamby shield GAMBY: Arduino Retro Gaming Shield and the Video shield (Video Game Shield | Wayne and Layne) and are still struggling with the sound engine.
TEAM a.r.g. http://www.team-arg.org