How One Assassin's Creed Valhalla Developer Created The Isu Language From Scratch

In September 2011, Antoine Henry, then a game designer at Ubisoft Paris, was about to fly back from a trip to Saint Petersburg. Passionate about languages for many years, he browsed his tablet for a book about Russian to read during the flight. That was when he stumbled upon “The Language Construction Kit” by Mark Rosenfelder, a book offering basic tools to create a new language. Henry read the book in one sitting and decided to delve even deeper into linguistics, eventually leading him to create his own languages in his free time.

What he didn't know then is that less than 10 years later, he would be asked to come up with a brand-new language for the Isu, the ancient civilization of beings from Assassin’s Creed lore that existed on Earth before humans. This is the story of how he did it.

One evening in a Montreal bar

After studying game design at the National School for Video Games and Interactive Digital Media (ENJMIN) in Paris, Henry joined Ubisoft on April 1, 2007, to work on the Rabbids franchise and consult on Just Dance. “I joined the Watch_Dogs team right after the game was announced at E3 2012, and worked on various activities offered in the game's world,” Henry recalls. “In the summer of 2014, I joined Ubisoft Singapore to work on Skull and Bones. Then I started working on Assassin's Creed Valhalla in 2018, mostly on gameplay elements related to ships. We also helmed The Siege of Paris DLC.”

In November 2018, Henry traveled to Canada to meet the teams at Ubisoft Montreal, where the Assassin’s Creed franchise was born. One evening after work, the game designer found himself chatting in a bar with Darby McDevitt, Valhalla's narrative director. “We talked about my passion for languages, and he said, 'It would be awesome to create an actual language for the Isu. Fans would love it.'”

It was an idea that McDevitt had been considering for several years. “When I was young, I read ‘The Lord of the Rings,’ and was fascinated by the languages Tolkien had invented,” says McDevitt. “But I especially remember the day the Star Trek team released a Klingon dictionary. That really reignited my interest in creating languages. And creating a language for Assassin's Creed was an old idea that we had sometime around the creation of Assassin's Creed Origins. But we didn't have the time or the resources to do that back then; it was more like a dream. I remember our discussion with Antoine, and as he had this passion for languages, I mentioned this idea I had a long time ago.”

Minerva's message

At the end of Assassin's Creed II, after players fight and defeat Rodrigo Borgia in the Vatican vault, a hidden temple is revealed that contains a message from Minerva warning the player of an impending catastrophe. This sequence was also used to introduce a new revelation to the saga: the existence of the Isu people.
The Isu are an ancient and technologically advanced civilization that lived on Earth before humans. In the world of Assassin's Creed, the Isu created humans with the goal of using them as servants. Messages written in the Isu language can be found regularly in the games, designed to pique players’ curiosity.

“At the time, artists created a series of glyphs and symbols that weren't supposed to mean anything,” Henry explains. “Their purpose was mostly to represent the civilization in an aesthetic way. Placed on textures throughout the games, they made it seem like writings related to the Isu people actually existed. For instance, you could see them on Rodrigo Borgia's staff.”

“In Assassin's Creed II, the Isu were intended to remain very mysterious,” says McDevitt. "As we were only supposed to do a trilogy, we weren't supposed to go too deep into the Isu lore. But we made more games, and a game like Brotherhood really helped us to start exploring this civilization, even if we didn't consider them as an entire historical entity until Black Flag. Then, in Unity, we created the Isu name, which is inspired by Ancient Egyptian and means 'the ancient ones.’"

Production teams continued to work Isu writing into the games, although without establishing a common logic from one game to the other. This led to the language taking various visual forms depending on where the story took place.
That's why the conversation between Henry and McDevitt was a turning point: Valhalla’s team had a unique opportunity to create a brand-new aspect of their game for players to explore. It helped that Henry was not just a creator who loves languages – he had already built languages for other games, including Spiders' GreedFall, released in 2019. And working on such a project was compelling to him.

“Obviously, I thought it would be awesome,” he recalls. “The next day at work, we had a number of meetings on other matters, so we didn't talk about it. Eventually, I left Montreal without broaching the subject again. I figured it was just a passionate conversation that might not amount to anything.”
But a few weeks after this unexpected exchange, the Montreal studio called and asked him to create a language for the Isu people, and to implement it in Valhalla. “I had already created languages in a professional setting, but it wasn't my actual job, so I was very excited to be given this chance,” Henry explains.

“We needed a real language, because it's the most important thing about a culture,” says McDevitt. “It's the repository of all your habits and beliefs. And it would allow us to do fun world-building things, like hidden messages, that allow players and dedicated communities to have a lot to discuss and create around the game. And thanks to Antoine, we were able to start working on it.”

The Voynich Manuscript

Before starting this colossal undertaking, Henry had to immerse himself in the franchise and look for traces of the Isu civilization in order to maintain as much consistency as possible within the existing universe. So he set out to analyze content sequences, either by playing the game or watching walkthrough videos on YouTube, particularly those mentioning or alluding to the ancient people.

“I really wanted to avoid sweeping away everything that was already in place, so I focused on giving the illusion that all the elements had always been there. But since these language elements weren't created with this purpose in mind, it was very difficult to make all the component parts work retroactively.”

Then a solution appeared in Assassin's Creed IV: Black Flag. Part of the scenario leaned on the real-life Voynich Manuscript. This illustrated and anonymous book from the early 15th century is known for being a coded pattern of letters. "An elegant, looping script of 25 to 30 characters runs from left to right in short paragraphs down the pages, interspersed with detailed illustrations," according to National Geographic. "The renderings show doodles of castles and dragons alongside diagrams of plants, planets, naked figures, and astronomical symbols, all detailed in green, brown, yellow, blue, and red ink."

In Black Flag, this manuscript is presented as an Isu text that can be deciphered using the in-game Precursor Box. "It was perfect for me, because I had encrypted symbols in the lore that could be deciphered with a tool," recalls Henry. "I had everything I needed to create the illusion I was trying to set up." Leveraging the studies of the Voynich Manuscript, he was able to lay the foundations of the Isu alphabet.

“But of course, an alphabet is not enough to create a language,” he adds. “After all, you can write French words using Japanese characters. So I needed to define a grammatical system, a structure, and this language had to have something to say to the players.”

Indo-European Influences

If the Isu created humanity, Henry posited, then their language is also the precursor of human idioms. While there is no common root to all of the existing languages on Earth, he was particularly interested in the Indo-European language family.

“First off, it's the largest language family in the world. It's also the language family that is the closest to the majority of our players, who mainly speak English, French, or Spanish. So it made sense to go in this direction,” Henry says. “As this family's precursor, the Isu language would be more accessible to more of our players.” Rooting the language in this real legacy also reinforced the illusion that the Isu really did live on Earth, and that another history exists beyond the one we know.

According to Henry, creating a language usually starts with sounds, which are the main markers of its identity, its singularity. Building from the Indo-European phoneme register, he applied natural language evolution processes in reverse. For instance, if the sound “peu” became “feu” in some cases, it's also possible the other way around. Using this method, Henry progressively created sounds that could have led to Indo-European languages. These sounds then needed to be arranged, correlated, and finally used to create words using the same reverse-engineering technique.

“It was incredibly cool for me to start taking Indo-European words, and using an automated program to apply this 'de-evolutionary' pattern,” Henry recalls. “It felt like I was discovering a new language, when I was actually creating it.”

Antony Henry, the Linguist

After a number of tweaks, Henry started assigning each sound to a specific symbol, thus creating a complete alphabet. In the end, 1,000 words were created to form this language. At this point, the main challenge was to make sure that each and every player, when seeing this language, would be familiar with some of its linguistic mechanics. “From the very start, we knew that all our work would amount to nothing if no one could see it or understand it,” Henry recalls. “By coming up with a real language, we could really enhance the players' immersion in the game's universe. It needed to be the source of a mystery they would have to solve, to decode.”

Henry’s experience as a game designer was invaluable when, alongside the narrative team, he started implementing linguistic puzzles in the game. “Darby helped us make the right choices when integrating the language in the game,” explains Henry. “We decided to present the language as part of the main quest, so that everyone would know of its existence. This basically amounted to placing the first piece of the puzzle, to inspire fans to look for more.” In the end, Isu messages can be found not only in different parts of the game, fully written out, but also on the Collector’s Edition box, on the soundtrack CD, and on wall art. Most importantly, there’s also a “Rosetta Stone,” a set of translated texts that can be unlocked on Layla’s computer.

“At a certain point during his process, Antoine told me that he needed some translated stuff in the game, to work as a Rosetta Stone and help the players in their research,” says McDevitt. “The only thing I really did on this part is that I wrote poems and documents that I wanted to appear in Valhalla, and that Antoine later translated. It was also a way to indicate the main vocabulary we needed to prioritize, from a narrative perspective.”

Henry was even given his very own character in the game: the linguist known as Antony Henry. This nod to his expertise also extended into the real world and within Ubisoft, as Henry then set up Isu classes for the production teams. “We realized that there couldn't just be one person in the whole company who mastered Isu,” says Henry. “We knew this could be potentially problematic, and that I needed to be able to pass the torch.”

He then created a series of classes, starting with pronunciation, listening practice, grammar, and vocabulary specificities. “I wrote a sort of manual, which included all of these aspects – a grammatical reference, with the corresponding rules.”

A Collective Investigation

After the in-game elements were confirmed and implemented came the issue of following through on the mystery, to make sure that the players would notice the clues and investigate them. The game's community development team came together to work on this aspect, in particular to add extra clues, even after the release of Valhalla.

"We hid codes in various pieces of content, including our Twitter banner and the fan kit created for the release of the Dawn of Ragnarök expansion," explains Clément Dagonneau, community manager at Ubisoft. "The aim was to get players to download the Twitter banner, import it in Photoshop, and play around with the settings to reveal the codes we had added in there. They could then decipher some of the Isu messages included in our trailers."

For the launch of the second expansion in Paris, a secret was even hidden in the actual Saint-Denis Basilica, inviting players to go out into the real world to investigate after discovering an in-game clue. "I was really surprised to see the Isu language mystery gain such momentum and be solved so quickly," says Dagonneau.

Fans were quick to analyze the glyphs from the moment the expansion was released. Some Reddit users started asking questions about the mysterious symbols, debating among themselves, and sharing their discoveries. “At Ubisoft, we really wanted to kick-start the search, and then silently follow what the players would come up with on the social networks,” explains Dagonneau. “We only gave them a push in the right direction, and congratulated players for solving the Saint-Denis Mystery. That was one of the rare occasions when we actually communicated on the symbols. After all, solving mysteries throughout the ages is at the very core of Assassin’s Creed.”

A large part of this endeavor was helmed by Access The Animus, a group of fans that, since its inception in Italy, has analyzed every title in the saga. “Access The Animus is a fan initiative that was founded on May 11, 2013, and that has the objective of working as a hub for all things Assassin’s Creed, sharing news, creating articles and videos, livestreaming, and even organizing live events with fans,” explains Sara, a member of Access The Animus and a veterinary anesthetist for cats and dogs in real life.

From 2013 to 2014, players, including Access The Animus members, could access the puzzles published on the Assassin's Creed Initiates platform to come together and investigate. But over the following years, such opportunities became scarcer - until the end of 2020, that is.

“I loved the challenge that the Collector’s Edition riddle provided; that’s the spark that started it all,” remembers Sara. Little by little, the clues left by Henry and the team were revealed to players, who immediately started deciphering them.

“Marco, who founded Access The Animus, and I are lucky enough to live in Italy, where we studied Latin in high school,” explains Sara. “And while we were dabbling with the riddles, we noticed that the Isu language grammar and sentence construction did have elements in common with Latin.”

In the game, players also learned that Isu predates Indo-European languages. “That’s where we started seeing similar suffixes in different words of the language, which represented the similar grammar cases being used, and that’s what showed us the path to the solution,” said Sara. By exploring other languages, like Greek and Sanskrit, fans followed the Isu language trail, finally deciphering it at the beginning of January 2021, only a few months after the release of the game. This made Henry and McDevitt incredibly proud.

“I was zero surprised that they cracked it so fast,” confesses McDevitt. “We also see it with Elden Ring right now, but any passionate community has a huge capacity to work together, crowdsourcing information, datamining the game, and solving problems together. You have to be OK with the fact that your clever secrets will be found, and sometimes not the way you expected them to be.”

“It's always fantastic to see players becoming really involved with what we have created,” says Henry. “And in this case, we really felt like we were offering them something very personal. As for me, I was able to interfuse two of my passions: linguistics and game design. So it was even more intense than usual.”

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