In the mid-nineteen-nineties, Koushun Takami was dozing on his futon on the island of Shikoku, Japan, when he was visited by an apparition: a maniacal schoolteacher addressing a group of students.“Today, I’m going to have you all kill each other.” Takami was in his twenties, and he had recently quit his job as a reporter for a local newspaper to become a novelist.In the early two-thousands, very few computers could simulate, in 3-D, the behavior of dozens of characters doing battle across an island, and very few Internet providers could calculate whether a banjo hurled by, say, Bob, in Kansas, would strike the head of Sven, in Stockholm.In 2020, Warzone, the Call of Duty series’ take on “Battle Royale,” attracted more than a hundred million active players, generating revenues of about three billion.The story of that rise might begin in 2013, in Brazil, where Brendan Greene, an Irish Web designer, was living while saving up for a plane ticket home, following a divorce."