In his recent book Spelunky, Derek Yu writes about the process of designing his 2008 (and 2012 remake) game of the same name, and often refers to the difficulties introduced by the decision to generate levels randomly. He describes trying to make sure that every time a level is generated, it is new, challenging, and solvable: “The game’s first priority,” he says, “is to make sure that there is a path from the entrance to the exit that is traversable without the use of bombs, rope, or other special equipment.” Spelunky generates its levels with templates for rooms and patterns for smaller…