Hi MariotheDog.
I'm very grateful you tried playing my game even though you could not really try it.
There should be a setting for the music volume in the menu :)
Regarding the joining. It's a little bit odd that you couldn't join with that setup. It could be caused by an issue with the fact that the Horipad controller is designed for nintendo switch (if i'm not mistaken?) and therefore my general input event does not register the controller press as an event.
If you have another controller and it works with that I'd love to hear from you. Otherwise I just wanna thank you for at least trying.
Best regards, MonoSolid.