Nicely nicely
First game? impressed. Youve got the recipe for a challenging game, give it some pizazz and less annoyance (like adding a boat each level, i thought it was a bit of a joke ending the first level after one hit) but i like, it all starts simple. And with actionscript, if you enjoy it youll keep learning and with every game you make youll learn heaps more. Man, i look back on my old games now and its amazing how far ive come. I already halved the code in my last defence game with the stuff i know now, ill upload it soon when i polish it a bit. Oh..ho ho, keep an eye out too, 360 Blau Elite is on its way....
But back to being relevant, keep up the good work, startin with old arcade game concepts is a great way of figuring out code.