Way out in southeastern Flint County, Back o Beyond is the most isolated area in San Andreas. Its trees loom conspiratorially, their branches knitted together, creating a sense of gloom. As night falls, a fog rises, muffling the air. For some, it’s a place of tranquility, far away from the noise and fury of the cities nearby. But for others, this forsaken forest is home to an unknown terror.

In 2004, Rob Silver was driving his truck through Back o Beyond when he caught sight of something in the thicket. “Out of the corner of the television screen I saw a large, tall, dark figure,” he said. “It happened twice, both times during that first year. To this day, I’ve not come across the creature again.” Earlier this year, Kaleb Krimmel, a teen-ager from Michigan, had a similar experience. “I have seen strange figures in the fog before, but pedestrians can sometimes appear in weird places,” he said. “While this sort of computer error describes most of my encounters, this time was different. I was in Back o Beyond, walking up a hill. It was foggy out, but behind some plants I clearly saw a giant black figure. I aimed my camera to take a picture, but by the time I steadied the viewfinder it was gone.”

Silver and Krimmel are not the only players who claim to have seen Bigfoot in the virtual forests of Grand Theft Auto: San Andreas, a video game released in 2004 in which players assume the role of a young gang member, Carl Johnson, in a story that draws upon various real-life events in Los Angeles, most centrally the rivalry between the Bloods and Crips street gangs. The game, set in 1992 within the fictional state of San Andreas, a geographical amalgam of California and Nevada, sold more than twenty-seven million copies worldwide. If the game’s developers had included a rare occurrence of a Bigfoot character in the Back o Beyond, occasional sightings from the masses of scouring players would be inevitable. Within months of the game’s release, videos allegedly showing sightings of Bigfoot appeared on YouTube, while viewers debated their authenticity in the comments.

These discussions were muddied when some enterprising fans created a “mod,” or an alternative code that can be downloaded and installed, to insert a fabricated Bigfoot into the game, complicating the hunt for the “real” virtual Bigfoot. Nevertheless, nearly a decade after the game’s release, a number of communities continue to work to prove the authenticity of Bigfoot’s existence in the original game, and devoted users still upload photographs of unusual footprints and other pieces of circumstantial evidence to their Web sites. Silver runs one such site. “Many Web sites make the Bigfoot myth out to be some fan-made story that’s simply gotten out of hand,” he said. “In fact, the staff at the Grand Theft Auto Web site I contributed to at the time didn’t want anything to do with myths, and refused to have them catalogued. Last November, I set out to make the most comprehensive, informative Grand Theft Auto myth site on the Web.”

The Bigfoot debate of the game closely mirrors that of the real world, in which believers often clash with skeptics. Silver’s certainty in the creature’s existence is absolute. “I one-hundred-per-cent believe Bigfoot exists within San Andreas,” he said. Krimmel agrees: “I do believe the creature exists. I have encountered him more than once. I would say he is proven.” But critics say the myth’s disciples are fooling themselves. “Either they’re mistaken, or they’re lying,” said a skeptical forum user. “Myth hunters are determined to believe in myths despite all evidence to the contrary. Perhaps they want the myths to be true so badly that they’ve managed to trick themselves into seeing things that aren’t there, or they’ve made connections between things that aren’t connected. Maybe they’re just lying or stupid, or both.”

One crucial advantage the Bigfoot hunters in the game have over their real-world counterparts is that they’re able to communicate with the game’s creators. Grand Theft Auto’s developer, Rockstar North, has not been silent on the issue. Speaking to an American video-game magazine shortly after the game’s release, the lead level designer Craig Filshie said that there was “not a bit of truth” to the Bigfoot rumors. “If you look closely, you’ll notice that all of the screenshots are typically retouched versions of screenshots we created for magazines and Web sites before the game was released,” he said.

Filshie even went so far as to offer his own explanation for what Bigfoot-sighters might be seeing in the game: “San Andreas is an extremely complex game, with millions of lines of code. It’s entirely possible for strange things to happen, but none of them are intentional.” Terry Donovan, the C.E.O. of Rockstar, said, “There is no Bigfoot, just like in real life.” This straightforward denial from the game’s makers should have been enough to quash the rumors—as if God himself had told the world that there were no hirsute monsters roaming America’s tangled forests.

But a video game with a scope like Grand Theft Auto is a vast and multifaceted construction, built by teams of hundreds of people. It’s entirely possible that one artist or designer could have inserted an Easter egg like Bigfoot without the rest of the team’s knowledge. Indeed, some coders concealed a sex-based mini-game—which became known as “hot coffee”—that led to the company’s being brought in front of the U.S. Federal Trade Commission in 2006. It was a scandal that cost the game’s publisher, Take Two, more than twenty million dollars in lawsuit payments. If a fully developed mini-game, which allowed the game’s lead character to have graphic sex with women, could be surreptitiously included in the game, it’s no great stretch to believe that a single rogue programmer or artist could have quietly inserted a mythical beast.

Virtual Bigfoot skeptics have another advantage over their real-life counterparts: they are able to scour the game’s code in search of evidence. If there were no Bigfoot assets, like a graphic rendering, it would prove that virtual Bigfoot was a myth. Some motivated skeptics have spent countless hours scanning the code; they claim that, in the thousands upon thousands of lines of programming, there is nothing referring to Bigfoot. But some people are dubious of these claims; after all, how meticulous will an amateur, unpaid hacker be?

Despite its early denials, Rockstar has only added to the sense of doubt in recent years. When asked to comment on the rumors, a Rockstar spokesperson told me, “We’d prefer to keep an air of mystery surrounding the topic. Let the myth remain a myth.” Christian Cantamessa, a former Rockstar employee who worked as a level designer on the game, took a similar stance when I approached him. “It is a little like asking the U.S. government to discuss Area 51, isn’t it?” he said. “The only appropriate comment is ‘No comment.’ ”

For myth-hunters, the search for Bigfoot has provided an ongoing and compelling reason to continue playing the game long after the main storyline has been exhausted. Krimmel visits San Andreas twice a week in search of Bigfoot, taking an in-game camera with him on his excursions in the hope of photographing the creature. “I’ve beaten the game twice, and maxed out my stats, so myth-hunting is the only thing left to do,” he said. For Silver, the ongoing allure is in the chance to catch sight of something rare and wonderful. “There’s a one-in-a-hundred shot at finding him, in my opinion,” he said. “That possibility is why I return.”

Whether or not people are disposed to believing in or disregarding legends, the San Andreas Bigfoot myth appears to be self-perpetuating. As newer and younger players gain access to the game and read the online rumors, some are inexorably drawn into the story, and become active participants in its extension. It’s a worldwide phenomenon. Rhem Alhatimy, a fourteen-year-old resident of Kufa, Iraq, bought a pirated copy of the game a few months ago, on a DVD containing each of the PC titles in the long-running Grand Theft Auto series.

“I’d read the rumors, and decided to visit Back o Beyond myself,” he said. “It was about three o’clock in the morning. That’s when I saw it: a dark, creepy thing standing in the woods. I’m not one-hundred-per-cent certain, but I think that was him.”

“I will keep looking,” Alhatimy continued. “There is something in those woods.”