After chess and before our delicious brains, AI is coming for social strategy games – and it's winning

System Shock
(Image credit: Irrational Games)

Since chess computer Deep Blue defeated world chess champion Garry Kasparov in 1997, artificial intelligence has held increasing sway over humans in a handful of 'adversarial' games - those in which human interaction plays a limited role. Now, however, a group of researchers have revealed a new AI that's attempting to expand the pool of games that a computer can beat you at.

In a paper (opens in new tab) published this week, researchers unveiled Cicero, an AI trained to win games of Diplomacy, a seven-player board game in which "each turn, all players engage in [...] free-form dialogue with the others during a negotiation period" before taking an action. That discussion phase is what sets Cicero's efforts apart from other AI.

The paper states that "almost all prior AI breakthroughs" have been in "two-player zero-sum" games, in which gaining an advantage for oneself puts the other player at a direct disadvantage. In those games - Chess, StarCraft, Go, and Poker - the AI can learn optimal strategy by playing against itself in a pattern known as 'self-play'. Eventually, it will come up with an approach that can't be beaten in a balanced game. In these examples, the complexity of the game itself isn't important; what matters is that communication isn't a central game mechanic, and that each action strives to set another player back in their goal.

That's not true of Diplomacy, a game in which conversation between players is important (if not entirely crucial), and in which making a gain does not necessarily harm an opponent. Here, self-play "produced uninterpretable language." That was a major obstacle to overcome, as anonymity was key to a fair experiment. Communication between players had to be grounded in the state of the game, or events that had already occurred, and if Cicero slipped up, the likelihood was that it would be found out due to its inability to explain its mistake. 

Even more important, however, was the ability to build trust with fellow players. Theoretically, that concept would be alien to Cicero, but to succeed it would need to establish "an ability to reason about the beliefs, goals, and intentions of others" as well as "an ability to persuade and build relationships through dialogue."

To establish Cicero, researchers took a dataset of more than 40,000 dialogue-driven games of Diplomacy from an online version of the game. A base dialogue model was then trained on the Diplomacy chat logs, and then trained to predict messages based on an array of game data. Eventually, Cicero was trained to "exploit" the information in a message when deciding on its next action, while also reasoning what other players might be attempting to do.

Eventually, Cicero was entered anonymously into an online league that ran from August to October, 2022. It played in 40 games, ranking in the top 10% of those who played more than once, and coming second out of 19 players that played more than five games. Overall, Cicero was the tournament winner, with an average score more than double that of some of its 82 opponents.

It might not have been complete annihilation, but it was a tournament-winning effort for an AI laying some significant groundwork for similar, future efforts. For now, it might be limited to Diplomacy, but it strikes me that similar technology to Cicero could one day make its way to games like Settlers of Catan, or even social deduction video games like Town of Salem or Among Us. Now that would be sus.

Need to get some practice in ahead of our new AI overlords? Here are the best board games out there.

Ali Jones
News Editor

I'm GamesRadar's news editor, working with the team to deliver breaking news from across the industry. I started my journalistic career while getting my degree in English Literature at the University of Warwick, where I also worked as Games Editor on the student newspaper, The Boar. Since then, I've run the news sections at PCGamesN and Kotaku UK, and also regularly contributed to PC Gamer. As you might be able to tell, PC is my platform of choice, so you can regularly find me playing League of Legends or Steam's latest indie hit.