Very easy to play, an Atari 2600 sort of simplicity to it. I'd enjoy it if the enemies were more thoughtfully timed to the rhythm and came in more challenging formations, there's that one big jump in intensity when the music picks up but otherwise the one-by-one trickle is a cinch. Blocking a whole string of enemies with the shields would probably be quite satisfying. Good start to something and a nice tune! :)