Thanks for playing and for the feedback! If you do have the time (and motivation) I'd love if you could try the final submission as I did sneak in quite a bit of improvement in the final day. The 2nd level was only added in the final release (selectable directly from the main menu or automatically loaded after completing) the first level. It is definitely brief though, yes. In 4 days solo work I'm afraid I simply didn't have time to add any more within the game jam, though I do intend to add more going forward. The music...I wrote a few pieces within those 4 days and wasn't happy that any of them fit the game. I've since composed this piece which I'm a bit more happy with but I won't be updating the game until the jam is completely finished. I don't know how it works in terms of the submission, but I don't want to inadvertently cheat by making changes after the jam finished but whilst the voting is still active.
(P.S. The keyboard controls are listed on the game's page. Again, I'm afraid I simply ran out of time to create graphics for both keyboard and gamepad inputs.)