That was a very good game. I enjoyed it. I loved the music. Could you tell me the title of the song and where you find it? I wonder now why nobody left a comment about your game. Nevertheless, I also think you could improve it a little.
First, the shooting system. It's a bit confusing. When I aimed and shot at the planes, sometimes I couldn't destroy them. I guess the shooting system of your game is special and intended. Therefore, I think you should mention it in the tutorial.
Second, for the items, same problem than the shooting system. I didn't know if we could use them endlessly or just after a certain period of time. If it is the case, maybe add a timer or a gauge to know the next time we can use the item again.
Finally, maybe add the possibility of moving the ship (but slowly). Like one button is starboard and another for port side ;).
Hope this helps man. By the way, feel free to try also my game and leave me some comments. I will appreciate. You can play it through my signature.