well it's a good start
this takes some actionscript to do, nothing fancy, I mean I could make the game in 5 minutes
With that said, the rotation is a nice twist to something thats been done a million times
I suggest you make "enemies" that come from all angles rather than just top to bottom
itd be pretty simple, just give them a random x and y speed, and have a boundary that if they hit it'll either turn them around or restart them with a new random x and y