This game is awesome!!!!!!!!!!!! On normal, it's quite fun. Also, I actually think an upgrade system would be a bad thing...it would make it far too complex...
Anyway, I've always liked games like this...no matter the actual gameplay (turn by turn, or real time like this one).
3/5. While the concept is awesome, the game is a bit slow and boring. It would be nice if the enemies and bosses would actually aim, the bullets moved beyond snail speed, and the bosses didn't just involve sitting there for a god forsaken amount of time.