Music composition for kids

D. got Guitar Hero World Tour today, a birthday gift from DH, and spent the whole afternoon "composing" his own music. His first piece is called "Castle Wall," and his second is "Castle Wall II." It reminds me of the fun B. used to have with the music composition part of Mario Paint, but far more elaborate (and less cute). B. once made a very nice version of "Ode to Joy" with Mario Paint.