I just updated Music Pack Vol. 1 with some videos so you can see how it sounds before you download it now! The music is somewhere between proper retro music and something cleaner. I'm bad at talking about it but its intended to be used for video games. If you find that it works well for something else, that's obviously fine as well. Go check it out if you want to, or don't.
I've listened to all of the music previews. The calm tracks are as expected calm and moody. The upbeat tracks sound great as expected except for Upbeat 4 which doesn't sound upbeat enough for me. Menu sounds really slow or no vibe at all. Both fight and boss tracks sound uninspiring. They should boost player's spirit or something. Boss track should give serious vibe in which player is in danger or threat.
Before you ask how serious vibe sounds like, listen to Upbeat 3 track. That's how serious vibe usually sounds. In fact, Upbeat 3 track might work for either fight or boss track.
