Interesting idea. It's pretty relaxing sounding as it is now.
Does the music change each time the button is pressed, or each time the whole game is loaded?
Technically yes. It's in a pretty rough state right now, so at most it changes key and tempo. Pressing the button just pauses the music at the moment. It's a nice way to stop/restart the music without ugly audio pops.
I'm planning to make it more differentiated in future updates though!
The goal is to be able to use it as a "live" soundtrack for web games.