Great job with this! Very polished and fun. Love the quick pace and the variety of enemies. I really liked that there were powerups included. If you wanted to push this a bit further, I think there would need to be a way to balance the players abilities and pickups. It was pretty easy to keep getting shields, healing items, and rapid shots once there were so many more enemies. I think this actually makes the game easier the more you play. Maybe the rate of items dropped could be lowered to compensate.
That being said, this was a really well done project. Loved the art and game play. Good job!