I like your game idea!
I had a bit of trouble playing with only my keyboard (can't point & shoot with my laptop's trackpad). I think that the keyboard movement would be a little more intuitive if the player shot in the direction they're facing instead of using the arrow keys to aim.
Because of the controls (and/or my lack of skill), I wasn't able to explore the game as much as I wanted to. Really cool concept though, and fun presentation!