Really well executed demo. I'd say this is one of those games that would be made better by a little tutorial, wasn't sure what was happening at first, I wasn't aware of the second screen for so long I'm a bit embarrassed to say haha - but maybe that's part of the experience, trying to figure out what is happening and what you're supposed to do. Once I got it though, I enjoyed it.
This is the start of something really fun, with some objectives, making the projectiles do more than push things out of the way, etc. it could be something great, wouldn't take much - the art style is already there. Good job team!