Here's some pointers:
Great concept, but badly executed.
Make the lines thicker, so it doesn't look like it was drawn in MS Paint.
Hand-draw the blood.
The stick figure concept is simple and entertaining, so keep it. Make the sticks more realistic. Think about a human moves, and apply it to your sticks.
If yous guns are so goddamn good, why can't the rest of the graphics be, too?