The game/the music
The game is great, my only complaint deals with the music. Two things:
1. When I turn off the in-game music, it pauses Pandora's music as well. I have no idea why, but if there's a way to correct that, it'd rock. Not a huge issue, though, just means I can't rock out to both Pandora and your game. I wonder if it's just me, or if others have had this happen?
2. When I turn off the in-game music, it only stays off for that life, i.e. I turn it off, get killed, restart the same mission, and the music is playing again. That's extremely annoying (especially when you consider #1). So. Yeah. I don't code, so I'd have no idea how to fix that, but I'm pretty sure it's possible
The gameplay was great though, I'm still fighting with my PC being a lag machine and level 6, but I'll see if I can't finish it. Interesting idea, well done.