AFTER ZOMBIES is an excellent Zombie Apocalypse game written by a veteran in the RPG field. It's an attractive, easy to read book that provides everything a group needs to start play in one session. If you're interested in the Zombie genre at all, Chuck Rice has you covered.
Mechanically, AZ is more old school than new; this is not a game with "cinematic" or "narrative" combat. This is a game with rules for hit locations and wound infection; this is totally appropriate to the genre. Task resolution uses d1-100, so in that sense the game is reminiscent of Chaosium's system, but its uses of Backgrounds, Levels (but not classes!), and feat-like Perks will be instantly familiar to anyone familiar with the World's Greatest Roleplaying Game. It is worth noting that Rice wrote many successful products for d20 and d20 Modern in the indy gaming boom that followed the Open License. All that experience is in evidence here: AZ spends a lot of attention on the things zombie-hunters care about, like specific models of firearms, scavenging tables keyed to various kinds of buildings, and explosives.
There's a long list of playtesters in AZ, and while there is probably a lot of balancing that went into the back-end, where I noticed the playtesting was in the many many options for character creation. A common concern in a game of this sort is that all the PCs look more or less the same; AZ addresses that problem with 18 backgrounds, 23 "Traits" (optional character features), 16 Disadvantages (when a disadvantage comes into play, you get more XP, so they are incentivized) and 11 PAGES of Perks (think Feats) for every attribute and skill. Making your zombie hunter different than everyone else on the outside is up to the roleplayer, but AZ will make sure they play differently too.
The theme influences the game mechanics. Rice has come up with a couple of really neat genre-simulating rules. Killing things and exploring does not get you XP, because in a zombie apocalypse the only thing that matters is staying alive. The longer you live, the more XP you get. (Killing things and exploring might help you survive, but that's what adventures are for.) Every group has a "Unity" stat, which represents how well the group holds together, and Unity is influenced by many factors, including not just the best Leadership score in the group, but the kinds of government the group has chosen. Unity helps the group resist insanity and fear, which is also a major force in the game as PCs get worn down by the horror of the world AZ.
There's a lot of advice here for making your own setting, and the bestiary chapter includes not just a dozen different kinds of zombies, but also a lot of the human opposition you would expect in the AZ. A sandbox-style campaign setting has been included, ostensibly set in Virginia but easily ported to just about anywhere. There are factions (I particularly liked Detachment 7, which is d20 Modern's old Department 7 with a name change, but still trying to serve the federal government... if only there was one!), NPCs with motivations and secrets, groups that need things and groups that have what everyone else needs. It's a setting with a lot of potential conflict, and your players will have no shortage of things to do in it.
AZ is a solid zombie apocalypse game with a strong visual presentation designed by a guy with decades of experience in the field and a love of the genre. Buy it.
[5 of 5 Stars!]