Yuzo Koshiro wrote TWO completely different soundtracks for The Scheme because the PC-88 had two different sound chips and he just decided to compose for both. This was right after he left Falcom and finished Ys II, and you can hear that same melodic intensity in tracks like "I'll Save You All My Justice" and "Angry Fist."
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The YM2608 "Special" versions push the FM synthesis harder with richer layering, while the YM2203 "Normal" versions have this raw, punchy quality. "Perpetual Dark!" goes so hard for a side-scrolling action RPG from 1988.
If you care about FM synth composition at all, this is Koshiro flexing before Streets of Rage even existed.