Got round to playing your game at last. Short but sweet :) Got a lot of cool mechanics in, just I guess you were strapped for time to get more level content in.
I really liked it. UI was excellent, really slick. And of course the googly eyes. Ideas for improvement:
- stop the camera movement on the pause / upgrade screen
- add some sounds - these are so key for boom boom games :)
- maybe make the enemies more aggressive, it's a bit easy to dodge their attacks. Though obviously the first few enemies should be literal cannon fodder.