nice collision script, although thres a few inconveniences. like pressing a, and how if you make a shot its the opponents turn. but it still a fun game.
ok i found more flaws. you hittest is innacurate, you can shoot when your dead, theres no sheild like the original, i really dont think its possible to win(i think just making the enemies smaller and slower would fix that. the enemies are supposed to faster and slower depending on how many enemies you killed. the ship is way too big, his wings leave the stage. you can only fire 1 at a time(although it seems like you did that on purpose). and frankly i think that putting codes on Mc's inside attached movieclips is a horrible method to teach people. either use duplicate movieClip with the code on the original clip or use onEnterframe functions. overall i thinkits not that good. you dont know enough about the subject to teach people this