That was a nice little game! Although most things made me confused and frustrated in relation to the gameplay and the UI.
Some enemy attacks look like power-ups/goodies you can collect to gain any sort of advantage or health. Except they're not. And even if it should be obvious that they're not because of where they come from, if they appeared from the outside of the camera view, I would still think of them as something that wasn't harmful or bad.
For the game size that is given to us (the part where the actual gameplay occurs), there is too much on screen. Too many things to look at, to worry about. That's fine if we're late into the game, after a couple of levels. But this is right in the beginning, making the player feel overwhelmed with their experience.
The aiming/shooting system isn't really something I enjoyed, although it can be more of a preference than a flaw, really.
All in all, a nice game that has still a ways to go!