In the past two decades video gaming has gone from a nerdy hobby to a blockbuster industry, with revenues over five times bigger than the cinema box office. Today it is home to one of the largest tech mergers in history. In January Microsoft agreed to pay $69bn to buy Activision Blizzard, a game studio. Yet the megadeal may not go ahead. America’s Federal Trade Commission—one of 16 regulators around the world to have taken an interest—will probably say soon that it will sue to block it.