ByteDance has been in games for a few years, but not as a main line of business. The company is stepping up its push, targeting the more lucrative serious gamers. Two recent deals have signaled its ambitions: In March it acquired Moonton, a Chinese game company founded by a former Tencent employee, and bought C4-Games this month.

Moonton’s flagship title, Mobile Legends, is one of the most popular games in southeast Asia. That game has generated more than $880 million in revenue world-wide since 2016 across both the App Store and Google Play, with around 408 million downloads, according to analytics firm Sensor Tower. And that number doesn’t include gamers using third-party app stores. C4 has also been strong outside of China: Its Houchi Shoujo is one of the best performing games overseas from a Chinese company, due to its popularity in Japan.

All this comes at a time when China’s Tencent, the world’s largest game company, is also looking to expand overseas. The company’s PUBG Mobile is one of the top-grossing mobile games globally, downloaded more than a billion times outside of China since its launch in 2018. Tencent had more than half of China’s mobile-gaming market in the first half of 2020,  according to research firm Analysys.

It is easy to see why ByteDance covets the mobile-game market. Helped by stay-at-home gamers, smartphone gaming revenue grew 25.6% in 2020 to $86.3 billion in 2020, according to analytics firm Newzoo.

ByteDance’s vast user base gives it an edge in its push into games both at home and abroad. The young users of TikTok and its Chinese version, Douyin, are perfect targets for its own games. Douyin had 600 million daily active users last August, according to the company. And people are spending a lot of time on these apps. ByteDance’s offerings, which also include the newsfeed app Jinri Toutiao, accounted for 15.8% of users’ time spent on major apps in China at the end of last year, compared with 12.7% a year earlier, taking share from companies like Tencent and Baidu, according to data firm QuestMobile.

ByteDance has disrupted China’s online advertising market in recent years as its viral apps have drawn ad dollars away from traditional players like Baidu and Weibo. Tencent is still way ahead in games, but it may need to pay closer attention lest it find itself next in line.

Write to Jacky Wong at JACKY.WONG@wsj.com