Fortnite is without question the video game sensation of the year. It’s hooking everyone from schoolkids to the rapper Drake, to major league baseball players. Some fans were even blaming Red Sox pitcher David Price’s problems with carpal tunnel on a Fortnite addiction. Price, an avid gamer, says he and his teammates sometimes play the game into the wee hours of the morning.

So, what makes Fortnite so habit-forming? It gets more complicated, but the simple part of the answer is that Fortnite is simply a fun and thrilling game to play.

“The end of a game of Fortnite is always exciting,” said Emerson College student John Newton. “Your blood’s pumping, and if it's not you need to check your pulse,” he adds with a wicked smile.

Newton gave me a Fortnite tutorial at the Microsoft Store in the Prudential Center, taking me through the game’s most popular format: the Battle Royale.

In the Battle Royale, you are one of 100 players airdropped onto a remote island. Each player starts off with nothing but the clothes on their back and a pickaxe. You need to quickly find weapons and supplies to fight the other 99 players, who are all trying to kill you, and each other. The winner is the last one standing. That’s what gets the pulse pounding for gamers like Newton.

“I don't think there will ever be a point where my heart isn’t beating out of my chest when it gets to the last two or three or four,” Newton said.

There are other video games that feature a battle royale mode — Minecraft featured a similar mod inspired by the “Hunger Games” movie in 2012. More recently, PlayerUnknown’s Battlegrounds (PUBG) had millions of people playing battle royale online. PUBG’s fans (and its developer) have even accused Fortnite of copying their format.

What makes Fortnite so special — and so popular? The simple answer to that question is, it’s free. Anybody who can get online can play, and you can play on just about any device — game console, PC, Mac, iPhone.

“There are no competitive advantages for pay to play or anything like that,” Newton said. A player can buy ‘skins,’ which are simply different clothes and outfits (though often elaborate). But you can’t buy bigger weapons or extra lives. “You cannot buy your victories in Fortnite, you have to earn them. And that’s one of the things that I think a lot of people appreciate,” he said.

Fortnite has a kind of democratic ethos — everyone starts off with an equal chance; the rich and the famous are like the rest of us in the game. Once you drop on to that level playing field, you can even end up playing against celebrities like the rapper Drake. You can then share video of your exploits on social media.

“Some consoles have the ability to record game play, which you can upload to platforms like YouTube and Twitch,” Newton says. "We’re in a fantastic age for social media, so those clips can go viral almost minutes after happening.”

Being so sharable, so accessible, and so free might have made Fortnite the perfect video game in the age of social media. But it’s poised to become bigger still, as Fortnite is becoming an e-sport.

E-sports are essentially video games with all the trappings of real sports. It’s now a “robust industry,” according to Kevin Mitchell, who established the e-sports program at Emerson College last year in response to the “strong demand for training at the collegiate level. There’s marketing, there’s production, there’s PR, advertising, analytics, there’s coaching, management, player development, all the regular jobs that you’ll see in the professional sports industry.”

Professional level e-sports are now huge spectator events, both online — and in the real world.

“In September there was a League of Legends championship that sold out the TD Garden,” Mitchell says (League of Legends was the most popular multiplayer battle game — before being dethroned by Fortnite). “They sold out the Staples Center, Madison Square Garden, The Bird's Nest in China where the Olympics was held, they had the World League of Legends championship and that sold out.”

Pro Fortnite teams are starting to form across the country. And Mitchell says more colleges are following Emerson’s lead, and adding e-sports to their curriculum.

“There’s currently seven to eight programs across the U.S., and there's currently 60 colleges in the U.S. that give scholarships to e-sport athletes,” he said.

And it’s just getting started. Peter Pham works for the e-sports company The Trade Group. He says the recent Supreme Court decision making it easier for states to allow online gambling means more money will come flooding in.

“I think it totally throws off the projection everyone had [that] e-sports, it's going to be $1 billion industry by 2019 or something like that. Now it's coming a lot sooner — it’s going to be a $1 billion industry by the end of the year,” Pham said. “So, no one really saw this coming immediately this year. But for those who are ready for it, it's going to be crazy.”

So, if you’ve been telling your kids they’re wasting their time playing video games — it might be time to reconsider.