The thought of a zombie attack is enough to keep any sensible person up at night. But you know what's even scarier? Watching waves of zombies trampling your nicely manicured lawn. That national (or at least gardener's) nightmare is realized in Plants vs. Zombies, a perennial best-seller. Game rules? The zombies advance, you bombard them with any number of flora, including ears of corn and frozen watermelons. That's just common sense, right?