The launch of Grand Theft Auto 5 has attracted unprecedented attention. Regardless of the amorality of the world the game creates, it is certainly an astonishing virtual landscape — a huge technological achievement for its British designer, Rockstar. Might there be a market for a London-based GTA 6, its criminal protagonists helicoptering through Tower Bridge and abseiling down the Shard, only to get stuck on the Jubilee line? On second thoughts, maybe it’s better left in southern California.