There are some well-established rules when it comes to making a successful online shooter - character progression, unlockables, and a stable multiplayer component are all big pluses - but converting a cartoony tower defense game into an online frag fest isn't exactly a common starting point. But that's exactly how Plants vs. Zombies: Garden Warfare was born, and somewhere within the smoke of an exploding Chili Bean Bomb, a layer of purple goop from a Chomper preparing to consume its next victim, and the toxic haze of a Zombie Stink Cloud, the relentless charm of the franchise has managed to fuse brilliantly with an unlikely genre.