OpenAI versus Humans: We estimate the probability of winning to be above 99%

Shounak Sengupta

6th, Aug, 2018

*Cover Image source: @BeyondTheSummit

The much-awaited show match between the OpenAI and a team consisting of high MMR Dota personalities was played out yesterday with the system dominating the Humans for the first two games of the series and only losing when all odds were stacked against them. What the Dota community once dismissed as a near impossibility is slowly becoming reality and the outcome is impressive and scary at the same time.

The OpenAI Dota bot first made its debut at TI 7 where it beat some of the world’s best players in a 1v1 mid Shadowfiend matchup. What was most impressive about the bot was its ability to learn and adapt and even when it lost a match, it would be able to learn from it and never allow the same strategy to be used against it. Soon after, the OpenAI team announced plans to design a whole team of OpenAI bots ready to play against five human players. Months of testing and development followed and we soon found out that the OpenAI team was already beating high mmr stacks on a consistent basis. A show-match was announced featuring the bots and ex-pro players/personalities like Blitz, Merlini, Fogged, MoonMeander and Capitalist, the results of which are before you.

The rules

It was made clear that the bots were limited by certain aspects which meant that the games were quite different from the normal Dota that we know. To start off, the hero pool was limited to only 18. The patch in play was 7.16 and each hero had their own dedicated courier which could not be sniped. In addition, items like Necrobooks and Manta Style were off limits as the microing capabilities of the AI would be far superior to Humans and the team didn’t want an unfair advantage going to either side.

How the games went

To kick things off, the AI played against a team of 5 random players chosen from the crowd. The match was quite one-sided with the AI using a death-ball push strategy and effectively closing out the game within 15 minutes. Most of the players were low skilled and were unable to react thus making it an extremely one-sided game.

Credits: u/PizzaForever98 

In the first game against the Human Team, we saw the AI adapt a similar death-ball strategy. They absolutely dominated both the side lanes crushing both cores played by Moonmeander and Merlini but it allowed Blitz’s Shadow fiend to pull out ahead. The fights always went the way of the AI with most of the heroes getting obliterated before they could land a single spell. The Humans banked on Fogged’s Blink Dagger to be able to take good team fights but an instant hex from Lion when he blinked in put an end to any hopes the humans had.

In game 2, the Humans started abusing invisibility by picking a Riki and rushing a Shadowblade on Blitz’s Shadowfiend but it was in vain as once the AI team started sticking together and pushing down towers, no one was able to even approach them. This time it was Merlini’s Death Prophet who seemed to have minimal impact and was unable to cope with the frequency of fighting in the game. In game 3, the developers allowed Twitch chat and the audience members to pick the heroes for the OpenAI which resulted in a very awkward draft. Once the game got underway, it was evident that the AI was baffled by what was happening, choosing to make some truly weird decisions that made it seem quite broken. The Humans took the win relatively easily despite the AI trying its best to delay and cut waves. The series ended at 2-1 for the AI but to be fair the Humans were only able to win after forcing a bad draft onto the bots.
The quirkiness of OpenAI

As a person who has followed, played and watched a lot Dota over the years, the whole Open AI experience was a truly incredible experience. We often think that Dota is a wonderfully complicated game but with the magic of technology and innovation, we had an AI system beating some of the smartest and best players in the game. Sure there were limitations and rules but just the way the bot went about and did things was truly a weird and unseen form of Dota. Here’s what stood out the most:

Inability to understand items fully: Both wards and Smokes were used very ineffectively by the AI. It almost seemed that they were forced to use it rather than using it to have an actual purpose. They were left quite confused by Blitz’s Shadow Amulet usage and unsurprisingly learnt it themselves and started using it in the third game of the series.

Looking at the game differently: Nowadays we often look at Dota in terms of efficiency and map control but the bots pretty much grouped up with the siege creeps and didn’t really have any concern with regards to what we call the laning phase. They were more than happy to put 4 heroes in a lane right from minute 1.

Aggressive style: The bots were super aggressive and instantly jumped on heroes when they showed up to a lane. They often gave priority to kills and damaging enemies rather than farming or last hitting. As a result, they often ferried out salves, clarities and mangoes to sustain themselves meaning that they never really picked up a massive net worth advantage over the enemy despite being a good 20 kills ahead.

Learning on the go: A very interesting mechanic that may or may not have been a bug was the bots using a pause after the humans had used it to fix a technical issue in an earlier game. This was a really unexpected result that didn’t have too many explanations. But it was not only this, they also adapted to using the shadow amulet after learning from Blitz in game 1.

Mechanically superior: This one was always expected and it often gave the AI an unfair advantage where they were able to execute and do things with reaction times that would not be possible for a human. Here’s an example.


In the end, the OpenAI team seemed pretty happy about the results and mentioned that they would now be facing a team of pros at TI8.



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