A typo in a Civilization 6 data file is messing with the AI's priorities

Update: Firaxis has confirmed that the spelling errors are a mistake. In a brief statement sent to PC Gamer, the developer wrote: 

“We’re aware of a community-reported bug that has a minor impact on AI behavior. We’ve also made sure that everyone knows that I goes before E except after C… or other weird exceptions. Thanks to all who helped bring this to our attention and there will be a fix included in our next update.”

Original story: There's a story going around that sounds too improbable to be true: that Civilization 6's AI leaders have been acting strangely all this time because of five misspellings in a data file. The likelihood that Firaxis wouldn't have noticed such an obvious error for so long seems minuscule. And yet, inside one of Civ 6's loose data files, Leaders.xml, are the following five lines: 

<Row Item="YEILD_PRODUCTION" ListType="DefaultYieldBias" Value="25"/>
<Row Item="YEILD_SCIENCE" ListType="DefaultYieldBias" Value="10"/>
<Row Item="YEILD_CULTURE" ListType="DefaultYieldBias" Value="10"/>
<Row Item="YEILD_GOLD" ListType="DefaultYieldBias" Value="20"/>
<Row Item="YEILD_FAITH" ListType="DefaultYieldBias" Value="-25"/>

In each line, 'YEILD' is a misspelling of 'YIELD.' That wouldn't matter if it were misspelled everywhere, but 'yield' is written with the correct spelling in every other instance across all of Civ 6's data files.

The misspelling was noticed by Something Awful forum user Straight White Shark (though they say in the thread that they weren't the first to pick up on it), and I've verified that the 'YEILD' lines can be found in a fresh Civ 6 download, though it isn't clear whether the mistake was always there, or if it was introduced in an update.

Testing with and without the typos

Shark and other Civ players believe these table entries are meant to set the AI leaders' default priorities, which are then modified by their various preferences and agendas. The effect should be that, by default, each leader prioritizes production and gold over everything else, and gives the least priority to faith. Popular theory has it that these misspellings are causing the default values to be ignored, explaining why some AI civs seem to put too much energy into religion.

By running two automated 151-turn games using the same Civilizations, each starting in the same spot on the 'true start' Earth map, Shark did find that fixing the misspellings created a noticeable difference in the AI leaders' priorities—they produced less faith overall, and more buildings and science.

I have been able to create reproducible results with the same basic methodology. By using the true start Earth map, I can run identical games using the Autoplay mod and produce identical end-of-game graphs, provided I don't change anything between tests. When I fix the typos, though, the graphs change. For example, Pedro II produces less faith-per-turn at the end of 100 turns when the typos are fixed.

The faith-per-turn graph after 100 double-speed turns without the typos fixed.

The faith-per-turn graph after 100 double-speed turns with the typos fixed. (Note the difference in the Y axis values.)

To confirm that I was definitely making a difference, I set faith to 1,000 and all other yields to 0. When I did, Pedro II's faith-per-turn skyrocketed within 50 turns, and the other civs in my test trended up too. Even Queen Victoria built a Holy Site, which she didn't do in any of my other tests. I tried the same thing with the typos uncorrected, and the graphs reverted back to 'normal,' as if I hadn't changed anything from my first baseline test. With the misspellings in place, the lines don't do anything.

It's possible that the misspellings were introduced in a recent patch, and weren't there all along. It's also possible that Civ 6 is actually behaving as intended despite the misspellings, as different default values might be set elsewhere, making these five lines obsolete. But who would take these lines out of commission with typos, rather than by commenting them out?

I've reached out to 2K to find out if Firaxis is aware of the misspellings, and whether or not AI leaders are truly supposed to deprioritize faith, and just haven't been. 

If you don't want to go editing the xml file yourself, you can download this mod on the Steam Workshop to try playing Civ 6 with the typos corrected. For more data, a few players are testing variations of the typo-corrected values on Reddit.

Tyler Wilde
Editor-in-Chief, US

Tyler grew up in Silicon Valley during the '80s and '90s, playing games like Zork and Arkanoid on early PCs. He was later captivated by Myst, SimCity, Civilization, Command & Conquer, all the shooters they call "boomer shooters" now, and PS1 classic Bushido Blade (that's right: he had Bleem!). Tyler joined PC Gamer in 2011, and today he's focused on the site's news coverage. His hobbies include amateur boxing and adding to his 1,200-plus hours in Rocket League.

Latest in Strategy
Mongolian throne room
Crusader Kings 3 saddles up for a long-awaited return to the east with its first Asian DLC, Khans of the Steppe
Manor Lords promo art - knight on horseback looking at a medieval village in the distance, viewed from behind
PCG's best city builder of 2024 is adding a map with a gigantic hill in the middle: the perfect spot for your next castle
Maximillian from Evil Genius 2
Rebellion CEO says Evil Genius 3 could happen but wonders 'what else could we do with it other than a base-building game?'
A city from 1800
One of the best city builders of the last decade is currently 90% off on Steam
Company of Heroes 3
Company of Heroes 3 is free to try and 50% off, so it's the best time to check out the beefy 2.0 overhaul
People swimming in a pool and lying on floats
Planet Coaster 2's spring roadmap splashes down, with 'round-bottomed flumes' coming in March and buildable restaurants arriving in April
Latest in News
Storm trooper hero
Another live service shooter is getting shut down, this time before it even launched on Steam
Possibility Space concept art.
Possibility Space owners sue NetEase for $900 million over allegations it spread 'false and defamatory rumors' of fraud at the studio that ultimately forced it to close
Valve soldier man on a pc.
2024 was Steam's 'best year ever' of users buying newly released games—but I wouldn't celebrate the end of the forever game era just yet
Money money money.
Valve tracked 1.7 million Steam users who joined in 2023 to see if they stuck around—they did, and they spent $93 million
Closeup of the new Copilot key coming to Windows 11 PC keyboards
Microsoft co-authored paper suggests the regular use of gen-AI can leave users with a 'diminished skill for independent problem-solving' and at least one AI model seems to agree
A lolporrit squeals in excitement while being driven in a moon buggie in Final Fantasy 14: Dawntrail, patch 7.2.
Final Fantasy 14 patch 7.2's trailer has me finally hyped to get stuck back in—and to go to the moon and pilot some mechs, because why not