PettingZoo is a Python library for conducting research in multi-agent reinforcement learning

Environments can be interacted with in a manner very similar to Gymnasium:

  from pettingzoo.butterfly import knights_archers_zombies_v10
  env = knights_archers_zombies_v10.env()
  env.reset()
  for agent in env.agent_iter():
      observation, reward, termination, truncation, info = env.last()
      action = policy(observation, agent)
      env.step(action)