Citizen Grim allows players to take it to the zombie horde in a Diablo-style action RPG setting, complete with plenty of unique weapons to unlock and statistics to manage. Players can hire their friends as mercenaries in the fight, played out in rounds comprised of countless waves of zombies as players build and defend various buildings used to generate resources.

Through a series of story-driven missions and challenges, players will unravel a conspiracy that has left Grim County frozen in the '40s and transformed its residents into Reapers, otherwise known as bloodthirsty undead. Of course, it's your job to find out what's going on and kill as many zombies as you can along the way.

This is the first truly core-focused social game that Zynga has latched onto, so it will be interesting to see not only how well Citizen Grim captivates the existing Zynga audience, but what exactly the publisher does with it.