Co-evolution of Spies and Resistance Fighters

We use an evolution strategy to evolve game strategies for resistance fighters as well as spies for the popular card game "The Resistance". In our experiment, players only communicate via observable actions. Players are judged by how they behave and not by what they say. Resistance fighters observe the behavior of all game players and try to deduce who is a spy by maintaining a score that represents who is likely to be a spy. Players likely to be spies are not taken on a mission. Spies use probabilities for their behavior. We use co-evolution to evolve resistance fighters and spies. Fitness plots seem to indicate that no progress is being made, i.e. we clearly see the Red Queen Effect in our experiments. However, the master tournament and current individual vs ancestral opponents method show that evolutionary progress is being made.