I'm glad you had fun with the game. Development wise, I had the song in mind from the very beginning, as well as the platformer mechanic. I started by labeling the beats in FMOD, and used an integration that lets Unity play tracks from FMOD and receive FMOD labels. Looks something like this:
These labels tells Unity when the jumps are, what texts to send at what parts of the song to loop. The map was made with the song and beatmap in mind, and I added some standard platformer tricks to make jumping less strict. The checkpoints helps limit the effects of any changes I make, so it was not too time consuming.