Original and fun.
You've created a great game here, very interesting idea. Excellent balance of power-ups, difficulty, and variety. It's really the perfect storm of a game. I have no complaints other than a glitch I encountered on the second to last level. I used the mystery morph power, and sometime during it, the enemies just stopped coming, and one rocket-copter was left on the screen, but it doesn't damage me, and I can't damage it. Thus I'm at a stand still, and had to close the game. No big deal I guess because of the saving method, just thought you should know it's there. Really good work guys, it was a pleasure to play your game.