A strange thing happened in the Civilization community r/civ on January 10, 2015. Inspired by similar, smaller-scale offerings by a Twitch.tv livestream and fellow redditor DarkLava (from whom he explicitly sought permission), user Jasper K., aka thenyanmaster, shared the first part of an experiment he was conducting wherein he put 42 computer-controlled civilisations in their real-life locations on a giant model of the Earth and left them to duke it out in a battle to the death, Highlander style (except instead of heads they need capital cities).

Since then, the practice has exploded in popularity. Reddit’s Civilization community has AI-only fever, but what exactly is so compelling about watching the computer play a very slow-paced turn-based strategy game with itself?

The early stages of Jasper K’s game saw most of the world engage in a gentle process of discovery and expansion into unoccupied land, Europe was an immediate clusterfuck. Casimir III’s early aggression put Poland on the wrong side of its neighbours just as a desperate power struggle ensued between around a dozen civilisations vying for control over the continent. It seemed like Poland would fall quickly, hemmed in on all sides and lacking the natural defenses that protected the likes of Carthage and Persia. But the Poles stuck it out, spurred on by a rabid (though bemused) online fanbase they couldn’t hear which chanted in unison some variation on “STRONK POLAND IS STRONK.” As I write this now, at 16 parts, 363 turns, and 4,130 years deep into the epic, still-unravelling storyline, Poland stands among the contenders for victory, with four (soon to be five) capital cities conquered and a red army that dominates Eastern Europe.

Thenyanmaster’s game of “what if?” has won such a following – particularly after a nod on the 4.8-million-subscribers-strong Bestof subreddit – that copycats have sprung up all over the place. There’s an African version, a Civ IV Rhye’s and Fall of Civilization mod version, one with just the British Isles, another with 20 civs on a map meant for just two, and at least 10 more – not counting the AI-only campaigns some people run privately to satiate their own curiosity or to compare with their favourite ongoing narrative. Now there’s even an official community game being organised and run (including a live Twitch stream) by subreddit mod TPangolin, with 42 civs and 42 mods enabled, which has dominated the community discussions since it was announced — there are separate threads for in-jokes, pre-game analyses, and trash talking, amongst other things.

For TPangolin, the secret to these games’ popularity is emergent storytelling. “People love to assign sentimentality and personalities to these AIs,” he explains. They get sad when their favourite loses or celebrate when it wins, with long comment threads and terse proclamations punctuating the major milestones.

“It’s frighteningly similar to watching sports,” TPangolin continues. “We know all the rules and how to play, so now for entertainment we watch multiple third parties battle it out. Perhaps we love these even more because we know that instead of athletes we’re watching historical world leaders battle it out in a fight to death on a global scale.”

AI-only Civilization games are the purest form of the Civilization concept: take the beginnings of recorded human history, tweak some variables, hit start, and marvel at how a series of interesting decisions leads to a radically-different present day.

TPangolin first explored the concept in 2014, a year after he began looking through the Official SDK for Civ V (a set of tools to help modders do their thing). He found that with a feature called FireTuner he could playtest the AI, sans human player, and began to setup games to run overnight – with the end goal of making a large, detailed political map of the world.

“In one such instance,” he describes, “I was playing a scenario called ‘Earth 2014’ – a scenario designed to recreate the political landscape on earth of 2014. I left the game on overnight, and when I woke up [saw that] the world in 2027 looked vastly different,” TPangolin continues. “Mexico had successfully invaded the United States, China’s words were evidently backed with nuclear weapons (having decimated half of Russia), India had forcefully colonised the Horn of Africa and, perhaps most surprisingly, Argentina had recaptured the Falklands.”

CivFanatics forum goer Kjetil “Kjotleik” Hvattum has a similar approach, though his motivations are different and his playground is not Civilization V but rather its predecessor, Civ IV (with the Beyond the Sword expansion). Towards the middle of 2014 he found Kossin’s AI Tournament: Season Three post, which was the third rendition of an American-style league format devised by DMOC back in 2010. (Gandhi won the first two seasons; the third was never completed.) Inspired by this and Sulla’s Civ4 AI Survivor series, and driven by the desire to learn more about AI strategies in order to move beyond the Noble difficulty level, Hvattum began plotting his own AI-only tournament.

His AI Auto Play threads take a very different tone to those on Reddit. Campaigns are completed in advance, and the community is challenged with picking who will win from just the starting positions of each civilisation. “The participation has been good,” Hvattum tells me, “and the fact that at least one person has picked the correct AI in seven out of eight games thus far is a testimony to the knowledge the CivFanatics [community] has about [Civ IV].”

The CivFanatics style of AI-only game doesn’t differ as greatly from the in-vogue captioned screenshots method as it seems. Most matches in the tournaments are worked into narrative descriptions quite similar to those written by thenyanmaster and co, with the one exception that the narrator and most readers already know the outcome – making it mere flavour text for the main attraction of predicting long-term, whole-game AI behaviour.

That’s no easy task. In both Civ IV and Civ V the AI has more than its fair share of quirks. Wars are often fought with no real progress for millennia, dragging on to the detriment of both sides or ending suddenly when the stronger force brokers a peace deal just as they’re about to march into a city. Sometimes the quirks have a comic effect. In thenyanmaster’s game the Huns spent hundreds of years raiding and razing rival cities in the Middle East but never themselves expanded into that territory (to their ultimate downfall), content instead to tend to their farms and eek out a quiet existence. He calls this and the related skirmishes in the region “the war where gains are made but in fact no gains are made,” as in addition to a widespread bias towards razing (even when attacking from the sea) that only subsided as the leading technologists – India and The Shoshone – moved into the Information Age, cities have tended to flip back and forth between attacker and defender several times.

Hvattum notes that AIs in Civilization are pragmatic opportunists. “If they find themselves bigger and better than their neighbours, it is usually just a matter of time before a war breaks out and the big AIs swallow up the lands of the smaller ones.”

We see this in thenyanmaster’s game, where technologically-superior India is, in Part 16, in the process of plowing its way west, picking off all the small and mid-sized rivals in its wake, while struggling one-city minnows Morocco and Venice were left in peace for hundreds of years and then steamrollered without warning in just a couple of turns.

Computer-controlled civs are seldom consistent in their actions, however, and thenyanmaster says that his favourite part about the whole endeavour has been the unpredictability of the AI. TPangolin notes that “sometimes they pull off amazing feats that we thought were impossible, such as actually settling the Suez or Panama – allowing a canal city that cuts through a continent. Other times,” he continues, “they settle those crappy snow islands that have a single source of Stone on it.” When it comes to narrating these stories of AI war, the “players” (for lack of a better word) are just as in the dark as you are about why certain decisions are made and what will happen next.

That extends to the broader trend, too. Despite starting the AI-only craze, DarkLava and thenyanmaster are both perplexed that it blew up so big that tens of thousands of people would be tuning into their games and many thousands more into those of the spin-offs.

The general consensus is that it’s more of a passing fad than something with real staying power. But there are murmurings that this could be the next Eternal War. Nathan “TheRedditDinosaur” Dawson, who is approaching the end of his fourth AI-only campaign, believes there will always be people engaging in this world of playing by watching. “It’s opened a whole new perspective to the game, and a very interesting one too,” he says. “Why should it just stop?” Further than that, even, he thinks that the act of watching the AI battle with itself could well spread to other games, effectively becoming a gaming niche all its own. In some senses this has already happened, such as in AI vs. AI fighting game stream Salty Bet.

TPangolin suggests that the key to AI-only games’ longevity is that they remain accessible to a broader audience – with play-by-play commentary accompanying image or video feeds and expert analysis in the comments all written with an eye towards the novice just looking to be entertained rather than the insider who knows all the lingo and the rules inside out.

TPangolin has also put his money where his mouth is by organising the official AI-only 42-civ game in which the community votes for which civs to include. “The voting process is hilarious,” he says. People formed allegiances in the comments before the game had even started, campaigning for “their” civilisation to get voted into proceedings, and things soon took a turn for the predictably ridiculous. In addition to an ensemble of standard civs, the community voted in Nazi Germany, The Buccaneers, World War 2 Britain, Imperial Japan, Stalin’s USSR, Napoleonic France, and The Boers. “What a time to be alive,” TPangolin says, leaving unspoken the exciting possibility that we may finally have an answer to the question of who would win in a fight between Napoleon and Caesar.

This, as with most AI-only games, is set to domination victory only – which means that it doesn’t matter how much culture, science, or technology a civilisation has, or who’s out in front come 2050. I asked Nathan “TheRedditDinosaur” Dawson, who has tried running AI-only games with other victory conditions enabled, why domination dominates the picture. “It is far more interesting watching the civs trying to win through battling rather than turtling up and winning through culture,” he suggested, adding that the games in which he kept other victory conditions turned on – as is the default in Civilization V – ended anticlimactically.

“You find yourself screaming at the screen, telling the AI to declare [war] on the civ that’s about to win through culture, but it never happens,” he continues. “You just feel like you only got half a show; you didn’t see all the civs battle it out in a final deadly battle like you expected.”

War is inherently dramatic. It guarantees tension, if not conflict, and that’s essential to a good story. But more importantly, perhaps, it’s that war, like sport, sows division. People barrack for their favourite team and live vicariously through its triumphs and failings. And like every good sport, the AI-only Civ games have brought people closer together while at the same time wedging them apart.