Very cool game! Excellent audio, excellent visuals, and just really well polished overall. For some suggestions on improvement, it would have been nice to have a bit more strategy to the game, as I didn't feel too much need to keep getting upgrades once I had a basic loadout that kept winning. Also, while it's not a hard game to pick up, but a little bit of information about how to play would have been nice.
Overall nicely done!