Though the term didn’t exist back when I was a teenager, squatting on comic-book floors to thumb through expensive hardback editions, RPGs are an example of the kind of literature described by Espen J Aarseth as “ergodic”. These are books, like digital literature, computer-generated poetry and MUDs, where a “nontrivial effort is required to allow the reader to traverse the text”. And they are more common than you might think, especially in geek culture. Game books that allow you to “choose your own adventure” are ergodic, as are fantasy novels with extensive maps and world-building notes. But the RPG handbook pushes ergodic reading to its limit. By putting aside simple narrative storytelling and replacing it with detailed description, the RPG offers the total immersion in an imaginary world so valued by geek readers. The elaboration of leading characters, political factions and major historical events is sometimes a very dry exercise in world building, but done with enough skill it can spark a deeply satisfying response.