What if the Zombies stopped attacking just long enough to let the living think they were gone, only to show back up years later...and with the knowledge to wield weapons?
That's the premise behind Nation Red where the player will fend off Zombies wielding axes, pistols, and other deadly weapons that used to be reserved for the non-zombie types only.
Even though the user is restricted to a small area to fight in they can pick up abilities and weapons to help fend off the horde. Enough kills will earn the player a level in which they can choose a perk from a list and then continue on with their fighting. The perks range from health and weapon benefits, to special abilities that, for a short time, give the player an edge over the gun wielding zombies.
Co-op play allows players, either on the same computer or over network play, to team up to defeat the horde and live another day...or not.