The field of competitive video gaming is turning toward mobile as its platform of choice.

Competitive electronic gaming, known as eSports, has taken off in recent years. Some professional gamers compete in large stadium settings with an audience, often plugged into large consoles. Others stay home and play from their desktops or home consoles.

But now, as with so much else, mobile is replacing these heavier setups as the platform of choice. eSports investors, developers and advertisers are betting on mobile competitions as the next big thing.

“With over 2.1 billion players worldwide, mobile is the most popular gaming platform in history,” said Andrew Paradise, founder and CEO of Skillz, a San Francisco–based competitive gaming company. “There’s no question as to whether mobile eSports will be a major driver for the industry.”

Skillz player competing in tournament

Superdata, a market research firm focused on video games, predicts that competitive gaming will be a billion-dollar industry by 2018. The global eSport market is currently worth $892 million in revenue with 214 million viewers, and expected to reach $1.23 billion by 2019 with 303 million viewers, according to the company. Coca Cola and ESPN have channels dedicated to eSport, while Nissan, Doritos and Red Bull are only a few brand names to be eSports sponsors.

Paradise predicts that the global eSports industry will award $250 million in prizes in 2017, and that 50% will be attributed to mobile. “In 2016, Skillz alone awarded over 30% of all eSports prizes to mobile gamers,” he added.

Champions of Fire tournament by Amazon and eSports Productions. Photography by Mark Gorman

Amazon has been investing heavily in eSports in recent years, and is focusing its efforts on mobile. The company hosted Champions of Fire, its first “casual mobile game eSport tournament,” in December.

“Competitive video gaming has seen huge growth, and we see tremendous customer value in expanding the tournament experience to include the casual mobile games played by millions of people today,” said Aaron Rubenson, director of Amazon Appstore, in a press statement.

Twitch, the live-streaming video platform acquired by Amazon in 2014, is also moving into mobile. Between August 2015 and May 2016, it racked up 100 million eSports viewers, totaling over 800 million hours of watch-time. Last spring, Twitch signed a three-year deal with developer Super Evil Megacorp to create Vainglory, a mobile game billed as “perfect for touch.”

Finnish mobile game development company Supercell is putting more emphasis on competitive gaming, launching the real-time multiplayer game Clash Royale in early 2016. A Clash Royale tournament held in Helsinki in April 2016 brought in over 2.5 million views.

Clash Royale tournament in Helsinki. Hosted by Supercell

What’s next? “Mobile and multiplayer will also drive the growth of AR/VR,” said Paradise. “This coming year, we expect to see hit games in both AR and VR. Mobile will provide accessibility for consumers, and multiplayer competitions will enable social network effects for a truly immersive experience.”

The mobile game industry is large and growing. Smartphone owners spent $41 billion on mobile games in 2016, according to SuperData; Pokémon Go alone generated $950 million in revenue. As mobile gaming and eSports converge, there is a big commercial opportunity for brands and advertisers to become part of the conversation.