A month and a half ago, OpenAI showed off the latest iteration of its Dota 2 bots, which had matured to the point of playing and winning a full five-on-five game against human opponents. Those artificial intelligence agents learned everything by themselves, exploring and experimenting on the complex Dota playing field at a learning rate of 180 years per day. Today, though, the so-called OpenAI Five truly earned their credibility by defeating a team of four pro players and one Dota 2 commentator in a best-of-three series of games.

There were a few conditions to make the game manageable for the AI, such as a narrower pool of 18 Dota heroes to choose from (instead of the full 100+) and item delivery couriers that are invincible. But those simplifications did little to detract from just how impressive an achievement today’s win was. The OpenAI team won against well-known Dota personalities Ben “Merlini” Wu, William “Blitz” Lee, Ioannis “Fogged” Lucas — all of them former professional players — along with current pro player David “MoonMeander” Tan and play-by-play commentator Austin “Capitalist” Walsh. Walsh sums up the despondency felt by Team Human after the bout neatly:

Never felt more useless in my life but we're having fun at least so I think we're winning in spirit.



Sure aren't winning in-game — Cap (@DotACapitalist) August 5, 2018

The OpenAI Five triumphed in convincing fashion in the first game, not allowing the human players to even destroy one of their defensive towers. The humans recovered a little in game two, conquering one tower, but they still got demolished. And finally, in a game three played purely for pride, the humans managed to squeeze out a win.

What stands out when you watch the matches is the apparent intelligence of the AI’s decisions and the inhuman absence of any indecision. The typical Dota 2 game, even on the professional tier, involves quite a bit of equivocation about whether to engage in a fight, try and shift it to a more favorable battleground, or run away from it completely. The OpenAI team just doesn’t need the processing time that humans require, which made its play appear unnatural — but only in the speed and crispness of the decision-making, not in the content of those decisions.

The developers of OpenAI noted that the OpenAI Five were losing to amateur players within their team back in May. By June, the AI had matured enough to defeat casual players, and today, it’s shown that it’s capable of overwhelming people who’ve been playing Dota 2 literally since its inception. The next goal for this rapidly evolving AI is to take on the very best Dota 2 players at Valve’s The International 8 later this month. That’s where the best teams will compete for the grand prize of being 2018’s Dota 2 champions, and one of the side shows will be a contest between them and the OpenAI Five.