Good Game
Pretty good game, played it through in one go, so its not a hard game to beat. Could probably use some more weapons..maybe some addons or bonuses to weapons, like(just off the top of my head) explosive rounds or something with more Knockback than already present. However the choice to bring in the minigun as a weapon is automatically a big plus, I mean, ya can't kill a zombie hoard without a minigun!
All in all I'd say decent game, just some more weapons and some addons/bonuses and you got yourself a great game! well done!