Impossible to kill anything.
As much as I would have loved to play the rest of this game and challenge myself to see how far I could make it, nothing would die when I shot them. The helicopter wouldn't go down, nor would the turret that was right in front of me. Either the hit detection is impossibly precise, or you just never added hit detection in the first place! Please, please make the enemies in this game possible to hit! It is impossible to win.
Other than that, for a game that was whipped up in five days, the graphics are nice and the controls feel great! I'm usually picky about controls but they're almost perfect. It might be because they're nice and basic. Sometimes simpler is better.
Anyway, though, just ease up on the hit detection and you might have a great game on your hands.