Great but...
The game was ficken great, I got all the way to level 4, then got one laser upgrade that changed my 3-green-beam canon into nothingness, I could no longer shoot any ennemy other than by shielding and eventually it all burned up, and then I had the unhappiness of restarting the level with the same accumulated powerups, which means no laser at all. Oh, and another upgrade wouldn't change anything, not that it mattered with the blastopod thingy one inch from it.
But other than this horrible bug, great game!! There's no 'functionality' rating in there, so I'm giving you a 10 anyways.