Nice Game
It's a great game and the concept is nice, but the fact is, you get maybe a 30 second "training", and I say it's training because it gives you a chance to to get your bearings, period before your screen is full with star ships and you have no chance at fighting them off without nukes, which you don't have as many as you need to be successful. You star with only a few fighters on your screen, and in less than a minute your swamped with enemies you have little chance of fighting off.
My suggestions:
1. Add level, and upgrades between levels, having an extra turret or two for the extreme difficulty you have set.
2. Tone down the difficulty early on, as said, you have about thirty seconds of what a game like this should be like before the inevitable massacre.
3. Make it so you know how many shot/time you have left on special abilities, and make it so you can see the ablity you are going to get before you get it.
My Report Card:
Concept: 9/10, relatively original
Playability: 5/10, as said, your swamped before you can say, Warp Speed Captain!
Repeatably: 4/10, why would I have that strong of a want to replay a massacre.
Graphics: 9/10, simply put, as a first game, the graphics are amazing.
Audio: N/A, sorry, I didn't have my speakers on. ''-_-
Overall: 6/10
Possibity for the future: 9/10, those edits above will help improve the game play overall.