Outstanding job! The original song sticks out over all the other elements regardless of what instrument is playing it, and fades into the original game sounds, which I love and I think is crucial when remixing classics. A lot of remixes I hear add roughly as many extra elements as you did (drums, synth, etc) yet make them so loud and prominent that it ruins the original song.
If I had to say there was any issue, it's that it doesn't start and end in a way that I could infinite loop it without noticing, but that's hardly your fault considering a once through had me loving it, and if I were really that dedicated I'd go cut off the first and last 30 seconds myself.