I love the backdrop that you chose for space. Fun game - fast paced.
I sometimes had trouble after losing a life where the right/left arrow wouldn't be responsive right away after the game restarted. If I survived this, it would eventually start working, but sometimes it caused me to die.
My arrow speed was just a little too fast at times, not giving me the fine grain control.
I liked the variation with some of the aliens shooting and some not. It made me have to decide whether I could get in and shoot or need to dodge.