The OpenAI Five paper, “Dota 2 with Large Scale Deep Reinforcement Learning” (arXiv 1912.06680), states in its abstract: “On April 13th, 2019, OpenAI Five became the first AI system to defeat the world champions at an esports game.” The agents learned the five-on-five game almost entirely through self-play reinforcement learning, training for about ten months before beating Team OG.