Thank you so much for the feedback!
LibGDX has come a long way since i last used it like 4 or so years ago so I would recommend checking it out again. One of the major things i noticed was assets management is so much easier.
I spent so much of trying to polish the game play, and balance it to where it wasn't too easy/hard and getting the enemy scaling right that I quickly ran out of time. (Also I started with just under 3 days on the timer so that's on me) The menu/game over screens were added in at 2am the night before the competition ended, so they were a bit of a rush job. I wanted to make an animated intro/tutorial and animations but just not enough time.
The sound issue is interesting as my music starts as soon as the game loads. I wonder if it comes down to the song not being loaded into memory before the browser loads the game and triggers the first play call. Something I'll have to look into.
But once again, thank you so much for the kind words.