Both Kongregate and the web sight you listed hav NaN for exp. Need to get that issue fixed. Also a speed up button to change the pace of the game, make it faster would be nice. Unable to really test the game due to the exp factor not working. 2 stars for now.
I like it a lot, a little tweaking and it would be great. Very old school feel. A bit better on collision detection. Shots killing you when they clearly missed your ship. Also I had one alien shoot at me from the bottom of the screen sideways. There was no way to avoid that shot.