Activision has long resisted the urge to put the heart of its blockbuster shooter franchise — the multiplayer, competitive modes — on mobile devices.   In the past, we’ve seen a standalone port of the co-op Zombies mode, a solid single-player campaign with curious strategic elements, and even a cynical freemium Clash of Clans-esque base building simulation — but never a proper online multiplayer experience.   Well, here it is. On the backs of the immense po[CENSORED]rity of F