Hello everyone! I've released an audio tool aimed for web game development: Orchestre-JS. Basically, it allows you to manage a dynamic soundtrack by adding and removing instruments on the go. It was made with simplicity in mind, you only have to provides your song's BPM, and the library will handle the rhythm for you.
This library was originally made for two of my previous games: Moog Memories and Blood Not Allowed. It should work on most JS game framework, including Phazer and Twine. With it you can do things such as change the music when the players encounter enemies, or when they enter a new area, or make elements of your game react to the soundtrack. It's also perfect for a rhythm game!
So far this home-made tool helped me a lot. So I hope it can now help other dev for musical games (musical games are the best)! If you intend to use it in your project, I would really enjoy to see it.