It was 1995, in the early days of the web, when the brothers Doug and Graham Walker decided they wanted to start a website. They hadn’t settled on a topic, but the two were fond of playing rock-paper-scissors in their garage, their matches filled with aggrandizing trash-talk. So, as a joke, they decided to devote their new website to the game. They came up with convoluted rules and regulations, a fabricated history, and cheekily named strategies about how to win. They dubbed it the World Rock Paper Scissors Society, not realizing their pet project would turn into what Doug calls “a unique viral experiment.”

Over the next 10 years, their site exploded. At its peak in the mid-aughts, the World Rock Paper Scissors Society was holding championships complete with black-and-white-shirted referees. They had corporate sponsorships from Microsoft and Yahoo! and a pot of $10,000 for the winner. The 2007 championships were televised on ESPN and Fox Sports, and Rolling Stone called the championship “a high-stakes Star Trek convention.” Last month, players took to a pub in London to battle it out for the title of U.K. Rock Paper Scissors Champion, and an international championship has been scheduled for spring of 2016. The way rock-paper-scissors achieved such visibility is perhaps a testament to how anything, no matter how silly, can earn a fandom. But it’s also proof of how a simple game resonates with people around the world, thanks to its nostalgic quality, easy gameplay, and history of transcending cultural barriers.

Rock-paper-scissors didn’t arrive in the U.S. until the 20th century, but it’s one of the oldest games used for making decisions in human existence, even if its history is muddled with legends and exaggerations put forth by Internet historians and Redditors (for example, the reason why the game is sometimes called “Rochambeau” is fiercely debated).

The earliest known references to finger-flashing games are a tomb-wall painting at the Beni Hasan burial site in Middle Egypt (dated to around 2000 B.C.E.) and centuries later on a scroll from Japan. Versions of rock-paper-scissors can be found in cultures around the world, but outside of North America it remains most ubiquitous in Asia. In Japan, the game is called jan-ken or jankenpon, and uses the same rock-paper-scissors finger positions, though a variation features a tiger, a village chief, and the village chief’s mother (who beats the chief). In Indonesia, the game is earwig-man-elephant, where the earwig overcomes the elephant by crawling up his trunk and eating his brain.

But whatever the interpretation, the game is pervasive, combining everyday utility with basic human psychology. People tend to think that it’s a random (and thus fair) way of making trivial decisions, but the game’s simple structure still allows for an element of strategy, making it an unlikely but fitting subject for a worldwide competition. While your best chance of winning would be to choose your moves completely at random, humans are naturally terrible at behaving randomly. Well-trained players who think of the game as a psychologically driven battle can use this fact and other influencers to increase their chances of winning.

Ironically, children are actually the most difficult to play against because they’re the most random in their choices, while adults who who are inclined to overthink their moves tend to be more predictable, Simmons says. More skilled players use gambits, which are pre-decided sets of three throws that help reduce the chance that you give away your next move. The Great Eight Gambits, the most common strategies employed, have names like “Bureaucrat” (for three papers used in a row) and “Fistful o’ Dollars” (for rock, paper, paper). “It’s about choice and the power of suggestion,” Simmons says. “The game itself almost disappears and it becomes this rarified force of will between two competitors when they both know what they’re doing.”

The Walker brothers’ website was partially inspired by the game’s psychological and game-theoretical underpinnings—which have now spawned legitimate research studies and many Internet articles proclaiming to teach you How to Always Win at Rock-Paper-Scissors. In a time when the Internet was first beginning to give people’s secret passions a platform, the brothers managed to hit a nerve and inspire a subculture. By the time the brothers threw their first “world championship” at a pub in Toronto in 2002, there was a line of people two blocks long in the middle of a snowstorm, determined to try their luck in the formal elimination contest or the seedy “street competition.”

“RPS is written off as a kids’ game ... but when you delve into it it’s one of the purest forms of competition that two minds can have with each other,” says the professional rock-paper-scissors player Jason Simmons (he goes by the stage name Master Roshambollah). Simmons, who travels to participate in international RPS tournaments several times a year, started the first American competition in 2001 at Burning Man. (He’s known for his paper-heavy strategy.)

Rock-paper-scissors competitors recognize they’re part of a larger joke. But their devotion to the game is also a way of poking fun at the spectacle of organized sports in general. When the Walker brothers founded their website, “Sports were overblown to an almost ridiculous extent—everything was becoming extreme,” Doug says. “It just seemed ripe for parody.”

Rock-paper-scissors isn’t the only nostalgia-fueled “sport” to have its own world championship—there are global competitions for marbles, tetherball, and four square. The 20th annual Air Guitar World Championships just crowned a winner in August. Participants in these childhood-game-turned-subculture bonanzas might not be entirely serious, but that doesn’t make the games any less fun. “Who doesn’t want to be the world champion at something, no matter how insignificant?” Doug says. “It’s like going back to childhood, but being able to bring a beer with you.”