I love the concept! The game is a bit hard to read sometimes because of the very blocky art style, but it's still a lot of fun!
The upgrades really feel like progress is being made, and I love the fact that one of them is just "Your bullet fires mini-bullets"!
They really make a difference on the battlefield... I mean, they would, if only the blue guy would shoot so I could see them in action, but that's too much to ask isn't it?! You're dying sir, SHOOT!!! D:
Great job! =D