Thanks! It was super fun making the sounds for it.

I used the python library midiutil to add the notes I wanted to individual midi files (single notes, success chords, failure chords, and new level / loop chords). Then I made a script to generate oggs for every instrument in the sound font i mentioned (this used fluidsynth + oggenc to map the midi notes to use each of the entries in the sound font) for one of the success chords, listened to them all, picked the one I liked best to be the sound and then did the same for _all_ the midis (every separate note, success chords, and failure chord).

I think I could have likely just used the sound font directly in the game and generated on the fly, but distributing the sound font itself was subject to their license terms, etc. But just using it to create midi tracks etc. did not have restrictions.