Without noise evolved controllers brittle. Population of GPs 30-50. With no constraints very difficult.
Tag is a children's game based on symmetrical pursuit and evasion.
Each controller is composed of distinct behavior components for pursuit and evasion. A player's fitness is based entirely on how well it performs in competition with several other players chosen randomly from the coevolving population of players. This approach avoids the need for an expert player as a fitness reference. In the beginning, the quality of play is very low. This provides a fertile field for slightly better strategies to exploit the weaknesses of others.