This song brings back memories.
When I was in high school, I spent most of one semester playing and beating Golden Sun on my Gameboy Advance in study hall. It was strictly for studying purposes.
The battle theme for Golden Sun kicks ass, actually the whole soundtrack does, but we're talking about the battle theme here. The synth line is great, but the part I like the most is the bass line. The bass line is amazing, so I felt the need to learn it on bass, and I did. Then I made it into this song.
I read somewhere that the composer for Golden Sun is a prog rock guy, and you can really hear this in the soundtrack. There's some tricky stuff in the battle theme, namely the awesome bass line, and that one arpeggio line. The drums in the original version have a very clear kick drum to it which adds to the prog rock sound.
To build on the already great battle theme, I also threw in the BOSS battle theme, which is even crazier and MORE progressive sounding. It's in 6/8, but then there are measures that switch to 5/4 and back. This is hell on a C+ drummer like myself.
The Boss battle theme also has a crazy fast solo to it that is originally synth. I almost did it on keyboard, then decided that'd be taking the easy way out, so I composed a similar sounding solo of the same speed on guitar.
The song wraps up with a revisit to the normal battle theme with a few changes. All in all I'm very satisfied with this cover, and I hope you are too.