This is really cool! Since you can add/create your own samples, and because it's open source, I can see people doing some crazy stuff with this!
I'm a bit of a dumb dumb, though. I was trying to figure out how to make a note stop playing, and it seems like it's the = button, but my square wave brain can't figure out how to work it.
It's probably in the settings somewhere; I just can't find it. :|