Chess is a relatively complicated game. This is proven in the first game of this 49th World Chess Championship already on move 7, when Jan Nepomnjaschchi, playing with White, moves his king’s rook to e1. He does so in a Spanish game, an opening devised by a priest named Ruy Lopez in the 16th century that has long been one of the most popular game starts. And yet Nepo’s natural-seeming move is so rare at this point, in this specific position, that his opponent Ding Liren sinks into deep thought in response.