Hey, thanks, this comment made my day! I've never really been sure how much the similarities between my solo music and game soundtracks comes through, but you're absolutely right, the soundtrack to this game in particular was very much a chiptunes version of the same kind of music I write outside of games. In a few cases, I actually did literally start with songs I'd written years earlier and reworked them as instrumentals.
My songwriting process for both is the same; I usually start with a lead/vocal melody and find guitar chords that fit underneath it. The challenge when working within the limitations of NES audio was that I couldn't play enough notes simultaneously to form full chords, so instead I would try to imply the tonality of the chords with a sparser harmony, usually with some sort of interesting rhythmic counterpart to the lead melody.