At first glance, Sea Hero Quest is a completely unassuming mobile phone game. Its mechanics are simple: You’re a boater, given a map to memorize. When the map disappears, you have to rely on recall alone to steer your vessel to the points you’re given.

In some levels, you have to find buoys hidden deep within mazes of ice; in others, you have to capture sea creatures on camera. But your success is based off about how well you can get around the virtual waters. That’s because for the first five years it was available, Sea Hero Quest was actually a science experiment, testing players’ spatial navigation by their age, country, and much more (with their knowledge). 

Traditionally, a neuroscience study might involve a few dozen participants. But Sea Hero Quest allowed researchers to study the gameplay of over 400,000 people. Now, in a new paper, they’ve used that data to determine one factor that might hurt navigational skills: growing up in a city with a regular street grid. The results were published in the journal Nature on March 30.

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“It’s very hard to generalize the findings that you make based on a limited population,” says Antoine Coutrot, a neuroscientist at the Centre National de la Recherche Scientifique in Lyon, France, and one of the paper’s authors. ”I think video games are … an interesting way to collect more participants from more, different backgrounds.”

Collaborators from several groups in Europe, including Alzheimer’s Research UK, Deutsche Telecom, and the University of East Anglia in England, initially created the game to help diagnose dementia. Neurodegenerative conditions eat away at your memory and capacity to find your way from place to place.

But just because you’re bad at directions doesn’t mean you should be concerned. There are many external factors, from your upbringing to your lifestyle, that can influence how well you can navigate. That’s where Sea Hero Quest came in: Its creators hoped they could use it to build a global baseline. The game asked its players to answer questions about their age, country, and more detailed matters, too, including how long they tended to sleep and the sort of environment they grew up in. 

“At the beginning, our initial aim was just to collect 100,000 people’s data, which we thought, at that time, was wildly optimistic,” says Michael Hornberger, a dementia researcher at the University of East Anglia and a coauthor on the paper. “We collected 100,000 people in the first two days after the game launched.”

Sea Hero Quest is no longer available to the public, but when it was, nearly 4 million people from all over the world made it through at least one level. While most of them didn’t play beyond that, close to 10 percent spent enough time on it to leave a treasure trove of information on their spatial navigation abilities—along with their demographics.

“We found out very quickly that, this data, you can use it for many different purposes,” says Hornberger.

The neuroscientists decided to scour for any patterns they could find. Unsurprisingly, regardless of where they lived, people tended to perform worse as they aged. But the team also found that the power to navigate correlated with a country’s wealth: Players from areas with higher per-capita GDPs scored better.

Gender seemed to play a role as well. Neuroscientists have seen that men are often better at navigating than women, but they aren’t sure why. Sea Hero Quest indicates that the size of this disparity correlates with a country’s rank in the Gender Gap Index: Women who lived in places with more gender inequality tended to score more poorly than their countrymen. Coutrot and his peers published those results in a 2018 Current Biology study.

Later, they wondered if the type of neighborhood a player grew up in would have any effect on their performance. The researchers began breaking down that data, which was provided by around a quarter of the game’s users. Those who grew up in rural areas or in suburbs tended to do better than native urbanites.

Street layouts from 10 Argentinian cities versus 10 Romanian cities
The author of the Nature study compared street layouts across different global cities, including in Argentina (top) and Romania (bottom). Coutrot et a. 2022

But cities aren’t the same across countries. In places like Argentina, Canada, South Africa, and the US, streets tend to be laid out in grids of predictable right angles. On the other hand, in areas like India, Malaysia, Britain, and much of Europe, roadways tend to go off at all sorts of angles, especially in city centers. This is often a result of older metropolises growing organically, tacking on new infrastructure over time.

On the whole, urbanites from countries in the first category navigated more poorly than their counterparts from countries in the second category. But players also tended to fare well at levels that reflected the street patterns they grew up around. Individuals who were used to right angles shone at getting around levels with regular layouts; those who were familiar with more hectic networks did better at comparatively random levels. In other words, the researchers think that being raised on a grid might make you adept at navigating other grids.

The makers of Sea Hero Quest aren’t the first to turn video games into a research tool. Researchers at the University of California, San Francisco, built Neuroracer, a driving game designed to improve its players’ cognition and memory. In 2020, the Food and Drug Administration approved the game as a treatment for ADHD in children.

Other groups have partnered with game developers to let millions of players mine scientific data for virtual rewards. In 2020 the multiplayer space exploration title EVE Online teamed up with various universities to create minigames where participants helped classify cell parts and hunt for exoplanets. Meanwhile, Borderlands 3 has a minigame that helps nutrition scientists sequence the DNA of human gut microbes.

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The difference with Sea Hero Quest is the players were part of the research themselves. Finding thousands, or even hundreds, of subjects for a human-cognition study can be tricky, Coutrot says. The phone game allowed researchers to collect data from orders of magnitude more.

“We did a quick calculation to see how long and how much it would have cost to do that in a classical way,” says Coutrot. “I think we calculated that it would have cost something like $10 billion. It would have taken us 10,000 years.” 

The nature of the game also meant that it cast a much larger net than traditional studies at a university or research institution, which can be biased toward participants in their 20s or from certain socioeconomic or ethnic groups. Sea Hero Quest’s community represented all ages and every inhabited continent on the planet.

Which means there’s plenty of data left from the game’s heyday to explore and learn from. Next, Coutrot and his collaborators want to see if spatial navigation changes depending on players’ level of education and how long they sleep on a daily basis. 

“This dataset gives enough work for several lives of researchers,” he says.