Thanks! The short version on the tech side is, it's all hand-written and very ad-hoc. There is some mid-level code for managing patterns and notes that's reused

Thanks! The short version on the tech side is, it's all hand-written and very ad-hoc. There is some mid-level code for managing patterns and notes that's reused across the demos, but the settings for how each instrument sounds, what kind of chord progressions to use, etc. is different for each demo. I didn't use any outside libraries, but I did package up the part of my code that actually plays sounds as 'npm/soundgen' (but it's not documented at all yet..).