THERE IS a scene in an early episode of the AMC series, The Walking Dead, in which a bald racist is giving a bloody good talking to as he’s handcuffed to a piece of roof piping. The show’s nominal hero, Rick Grimes, explains to him in no uncertain terms that, in light of the fact the zombie apocalypse is upon the human race, that his racial prejudice had better become a thing of the past and right quick. “There’s only us and the dead,” he hisses. “We survive this by pulling together, not apart.” That line cuts right to the core of Left 4 Dead, the four-player co-op zombie shooter released back in 2008. Unlike a lot of multiplayer shooters of the time where griefing, tea-bagging and generally doing your own thing in the multiplayer was par for the course (unless you were really into the concept of teamwork), Left 4 Dead forced players to unlearn a lot of selfish behaviour. The central conceit of Left 4 Dead is neatly summed up in Rick Grimes’s schooling of the racist mentioned earlier (his name is Merle, in case you care). If players didn’t work together as a team, they wouldn’t survive.