Zombies!!! 13: DEFCON Z is all about retaliation, with the military, the CDC, and others finally starting to mobilize against the zombie threat. As part of that effort, they try to recruit people with the most experience cutting through zombie legions — and that's you and your fellow players, the survivors who have lived out there in the shambler-infested wilds all these years. Zombies!!! 13: DEFCON Z is both a standalone game and an expansion for Zombies!!!.