Excellent job.
The game is exquisitely put together. Everything works amazingly well. and the "Robotron-esque" controls are a very fun diversion from the usual wasd + mouse controls typical in these types of games. And the array of colors present make this a very visually interesting game. This is an astonishing first flash game. Very well done!
On the criticism side, I personally feel that the lack of upgrades, gameplay variation, bosses, and other relevant progressive elements... cause me to lack the will to play it anymore. I had honestly gotten a bit bored of it after I realized that the only thing it offered for surviving was increased difficulty.
I understand that this is often times the nature of simple hi-score driven arcade games, but there are ways to keep the game interesting beyond a few play-throughs.
Anyway, like I said earlier, I think this is a fantastic first flash. It's apparent that you're a forward-thinking, talented, and creative programer. I have no doubt that your future submissions will not only be beautiful, and work exceptionally well, but will also provide enjoyable, challenging, and rewarding gameplay experiences.
-Keep up the great work bro!