Well...
I guess you simply need to improve a bit in 2 things:
1. Harmonic volumes. Try to make all the instrumetns sound like one, that is harmony. Try to lower the volume on some stuff.
2. Variation. But that might be on purpose for this song. As you are going to use it for a game, it's just good without too much variation.
/D - Got Time? Check my stuff :)