Mastering Stratego, the classic game of imperfect information

Game-playing artificial intelligence (AI) systems have advanced to a new frontier. Stratego, the classic board game that's more complex than chess and Go, and craftier than poker, has now been mastered. Published in Science, we present DeepNash, an AI agent that learned the game from scratch to a human expert level by playing against itself. DeepNash uses a novel approach, based on game theory and model-free deep reinforcement learning. Its play style converges to a Nash equilibrium, which means its play is very hard for an opponent to exploit.