Eh, its alright
Its alright, addicting, enough upgrades, the difficulty levels live up to their name..
Its very fun, blasting away at stuff with a photon cannon :P
But..it can get very boring. I am typing this now at level 20, and I just checked back at the game and Im dead.
Anyway, its boring because its just got the same feeling, blast blast sell blast repair blast blast blast. Firstly, it needs a couple of boss fights. Maybe a boss that fires lazors at you, then sends a small wave of say...5 tanks, then blasts again ect ect. That would make a change and convince someone to play on for more bosses.
Also, I noticed whenever I upgraded something, the prices of other stuff went up too. This makes it very very hard to get what you want for an upgrade. I suggest you do not make anything change when you buy an upgrade, apart from the fact youve bought the upgrade and THAT ONE UPGRADE YOU JUST BOUGHT raises in price and power ect ect.
Thats about all, I dislike the background but thats just my Opinion.