People aren’t just playing Fortnite in droves, they’re watching other people play it en masse as well.
Epic Games’ Fortnite accounted for more than a third of streaming video game views globally in May, up from just 2 percent in February, according to viewership on Mobcrush, a platform that lets gamers stream video across social media sites, including Twitch, YouTube and Facebook.
The free “battle royale” game, which became available on PC and gaming consoles last September, didn’t even launch on iOS — where it is more popular than on PCs or consoles, according to Mobcrush — till this March. Yet it took just one month on mobile to supplant Vainglory, which has been around since 2014, as the most popular video game to watch.
Fortnite isn’t even available on Android yet, so viewership will likely jump much higher when it is.
Hundreds of millions of people watch competitive gaming, known as eSports, and in the U.S. already outnumber NHL viewers, according to a March report by Bernstein Research. By 2020, eSports is expected to be the second-most-watched sport after the NFL.
The eSports market — which includes revenue from sponsorships, advertising and media rights — is currently worth around $900 million worldwide and is expected to reach $1.65 billion in three years, according to the report.
Fortnite generated $300 million in revenue in April through nonessential in-app purchases like clothing, and currently has 125 million players. It’s the fourth-most-downloaded iOS app in the U.S. and the No. 1 action game, according to App Annie. It’s bringing in more in-app revenue than Pokémon Go or HBO Now.
This article originally appeared on Recode.net.