If you think videogames are a nerdy pastime for out-of-shape boys gathered around laptops in their parents’ basements sipping on cola, you are sorely mistaken. Competitive gaming, known as electronic sports, or eSports, is a global phenomenon valued in the billions of dollars.

The industry is anchored by what is referred to as multiplayer online battle arena games, like “League of Legends,” where one or several players face off in a digital arena. Watching people play professionally has been popular in Asia for years, but it’s now also gaining steam in the U.S.

In fact, those powering the industry say it’s well on its way to becoming the next major professional sport alongside the likes of football and baseball. The biggest tournaments are already filling entire arenas, including New York City’s Madison Square Garden.

“The big events are already bigger than the biggest events in sports,” said Kevin Lin, chief operating officer of Twitch, the world’s largest videogame streaming platform.

“ ‘They are trying to build a new sports industry.’ ” — Patrick Creadon, director, “All Work All Play”

Twitch was acquired by Amazon.com Inc. AMZN, -2.32% last summer for nearly $1 billion. While the company is a platform for all types of live videogame streaming content, including streams of the popular soccer-game franchise FIFA, which was developed by Electronic Arts Inc. EA, +1.07% , eSports are its fastest-growing niche by far.

The average Twitch user spends two hours a day engaging with the site. Lin said it’s not unusual for users to stretch to the five-hour mark for some of the more popular players and events.

Related:Electronic sports explained in 5 pictures

In total, Twitch logs more than 100 million unique viewers a month, with those viewers racking up a collective 20 billion minutes of viewing time of the more than 11 million videos that are broadcast. The Twitch app has been downloaded more than 23 million times since its launch in 2011.

Fans fill the stadium at Intel Extreme Masters in Poland ESL Gaming

In 2014, Riot Games’ “League of Legends” world championship had roughly 27 million streaming views, more than the average viewership of individual games of the World Series and roughly the same as the number of people who tuned in for this year’s NCAA basketball final.

In March, ESL — the world’s largest eSports production and broadcasting company — counted 104,000 visitors to its four-day world championship event, the Intel Extreme Masters, and set a Twitch record with more than 1 million peak concurrent streaming views for a single event.

The lines outside of the Intel Extreme Masters were so long (see photo below) that ESL CEO Ralf Reichert joked that it looked like a Madonna concert. Reichert features heavily in the documentary “All Work All Play: The Pursuit of eSports Glory Live,” which is scheduled to premiere nationwide on July 21.

ESL Gaming

ESL, which produces original eSports content and hosts related tournaments and exhibitions, has vowed to bring more mainstream attention to eSports, starting with the lofty goal of filling 12 stadiums around the world with fans for eSports tournaments. Last year, it held events in four stadiums, including two in the U.S. — New York City’s Madison Square Garden and San Jose’s SAP Center.

See also: A college athletic scholarship to play videogames

ESL’s broadcasters sit at “SportsCenter”-esque desks providing play-by-plays with enthusiasm levels suited to the Super Bowl, which has helped competitive gaming appeal to a broader audience.

The company regularly streams eSports content six or seven days a week, but ESL also thinks there is room to expand to traditional television. The company is in “advanced discussions” with a couple of major networks, said Craig Levine, vice president of ESL America.

“This,” he said, “is more than just a fad.”

“ ’The big events are already bigger than the biggest events in sports.’ ” — Kevin Lin, Twitch

Last month, ESPN 2 made history by airing the finals of Blizzard Entertainment’s ATVI, +0.57% collegiate “Heroes of the Dorm” competition on TV for the first time.

With so many eyes on eSports, it’s no wonder game developers’ interest has been piqued.

The PC gaming market raked in $3.6 billion in revenue in 2014, according to a recent report conducted by EEDAR. Free-to-play games, the lifeblood of eSports, represented $1.11 billion of that and are expected to be the fastest-growing segment this year, rising to an estimated $1.29 billion.

“World of Warcraft” developer Blizzard Entertainment and “League of Legends” parent Riot Games have doubled down on free-to-play games. Blizzard’s senior manager of eSports, Kim Phan, said Blizzard is thinking about the spectator experience more than ever before.

. EEDAR

“Thinking about how eSports looked back in 2005 and how it looks now, the differences in size and scale are enormous,” said Phan.

Meanwhile, the top professional players, most in their early to mid-20s, are racking up huge sponsorship and streaming deals. The biggest players have been catapulted to eSports stardom. They go by pseudonyms, like LemonNation and Sneaky, and smile for pictures with eager fans, enjoying a celebrity status akin to Hollywood B-listers.

Playboy magazine recently ran an eight-page spread on the U.S. team Cloud 9, and the “All Work All Play” documentary premiering next month will showcase Cloud 9’s rise to the Intel Extreme Masters earlier this year.

An extract from Playboy magazine. Playboy

Corporate sponsorships are expected to reach $111 million in North America this year, according to a recent report from SuperData Research. The top players can earn millions of dollars over their career from prizes and endorsements, while teams monetize their brands through merchandising.

“It’s weird from my perspective,” said LemonNation, a 26-year-old member of Cloud 9, whose real name is Daerek Hart. “At first, at these tournaments, no one would know who I was, and now I can’t go through them without people stopping me for pictures or autographs.”

LemonNation in action Getty Images

As a team, Cloud 9 has raked in more than $1.8 million in prize earnings, making it the world’s 10th most successful team by prize earnings, according to SuperData Research. The top team, Newbee, based in China, has made more than $5.5 million.

Players can make even more money on their own if they build their own fan bases and strike lucrative streaming deals. Former “League of Legends” professional player Wei “CaoMei” Han-Dong earns more than $800,000 a year through a contract with Chinese streaming site ZhanQi TV that requires him to stream 90 hours a month.

While it’s hard to tell what will happen in another 10 years, everyone in the industry seems to be in agreement that they are on the cusp of something major.

“All Work All Play” director Patrick Creadon said those powering the industry are “building something that’s going to be around for a long time.”

This story was first published on June 25.