Some of my favorite gaming moments stem from co-op sessions with friends, and the chaos that can ensue when all your careful plans start to go awry. World War Z is a competent but basic shooter that seems designed to foster those sorts of memorable moments, and that is surely its greatest strength. It’s a good venue for a group of four friends to get together, topple massive zombie hordes, maybe save a few survivors here and there, and laugh about it when the results roll in.