I guess it's not fair to judge this as a traditional song, since the intention is for these different parts to play under different circumstances. I think the audio balancing here is good, and the instruments are pleasing to the ear. No issues with the mixing, either. I could definitely see this being used in a Flash game. That said, I feel like the melodies at play here are a little muted. I feel like they could be saying more than they do.
Overall, though, I think this is fit for the purpose. Good work.