OpenAI announced OpenAI Five, a team of five neural networks that plays 5v5 Dota 2. Trained via self-play without human data, it played the equivalent of 180 years of games against itself every day, using a scaled-up version of Proximal Policy Optimization (PPO) running on 256 GPUs and 128,000 CPU cores. Playing under restricted rules, it had started to defeat amateur human teams, and OpenAI set the goal of facing top professionals at The International in August.