If this were the box cover, I would probably not buy your game. I like the font, and the zombie/soldier are ok. But the white shine on everything looks cheap and so does the explosion + lack of background (sky).
I would recommend you find another artwork for the box cover. AND if you are unable to find a good enough artist for your budget, I would recommend you go with a classy (yet artless) box cover - with a beautiful font/design.
For example; buy a rabbit, slaughter the rabbit - mutilate the head. Print it on the box - with the title. I dunno, it will look gruesome, that's for sure. But perhaps my idea is a bit too hardcore for your game.
