From the introduction:
Against the Dead is a role-playing game in the tradition of your favorite zombie movie. Set in a world much like our own, the game pits your character against the unrelenting hordes of ravenous corpses that grow legion as each hour passes. Only the strongest, bravest, and most resourceful individuals have a chance of surviving this threat. Rarer still are those who can take advantage of the rise of the dead and not simply survive, but emerge as a master of the new world in the wake of its cleansing at the hands of the undead.
Based on the d20 Modern System Reference Document, Against the Dead presents a streamlined version of the rules that deals exclusively with zombies and ways to fight them. The only material you need to play the game is this book, a set of gaming dice, and a pencil and paper. Miniatures to represent characters and zombies are recommended, but not necessary. A CD or two of panicky ambient music can greatly assist the atmosphere of a game session, as can a soundtrack from any of the hundreds of zombie movies - good and bad - that have been produced over the years.