If you want to try these chord progressions in your browser, check out:

http://wildsparx.com/rhythatom/

Coincidentally I just finished it. Source is here:

https://github.com/wildsparx/rhythatom

In theory it should run in any Chrome/Chromium browser, but I've received several reports of rhythatom failing to play. Would appreciate any help or ideas.

If you look at: https://peterburk.github.io/chordProgressions/ChordProgressi...

There doesn't seem to be any indication of major/minor. One way to interpret that is "always use the diatonic." Which means only use notes in the key, which means chords (1,4,5) are major while (2,3,6) are minor. However songs can have non-diatonic chords.

If you look at Rhyathatom, it defaults to the well-worn 1645 progression - the 6 is explicitly minor, which makes it diatonic. Try making the 6 major and you get a different animal - kind of sinister! That's a non-diatonic chord.

Maybe the author accounted for this elsewhere.