It turns out that releasing a free-to-play game on smartphones can help you make more money.

Publisher Blizzard revealed today that more than 30 million people have played its online card battler Hearthstone on PC, Mac, smartphones, or tablets. And that’s a pretty decent number — although it doesn’t reveal exactly how active the community is on a monthly or daily basis. But that doesn’t really matter because the game is obviously catching on with many of the people who do play it, and you can tell that’s the case by how well it’s performing on the top-grossing charts on iOS and Android — and it’s doing quite well.

First, let’s look at the 30 million players in context. That’s a big number, but it isn’t groundbreaking for a free-to-play game. Keep in mind that developer Rockstar sold more than 34 million copies of its Grand Theft Auto V game, which typically costs around $60. In the world of free-to-play — especially on mobile — it’s not out of the question to have 30 million monthly active players. Candy Crush Saga from publisher King, for example, has more than 90 million people who play it every single day. On PC, League of Legends has around 70 million monthly active players.

Hearthstone is still not in the same league as some of the top free-to-play games. But that’s OK, because it is making money, which is a sign that it is great at retaining players and getting them to spend money.

Hearthstone is in the top 10 highest-grossing apps for iPhone in 16 different countries, according to App Annie. It is among the top 100 in 63 nations.

In South Korea, a huge market for mobile spending, it is the No. 7 top-grossing iPhone app. It is No. 12 in Canada, No. 14 in the U.S., and No. 18 in China.

In the United States alone, it is making around $155,000 every day, according to ThinkGaming.

And clearly, this success is largely due to Hearthstone finally rolling out on smartphones last month. The game debuted in March 2014 on PC and Mac, and it rolled out to iPad in April of last year. If found an audience, but it actually slipped down the charts several times and risked losing its momentum. That’s no longer the case as the game is exploding in popularity now that everyone with an iPhone or Android handset can get it for free.

And after adding content to Hearthstone and refining its mechanics for more than a year, Blizzard seems like it has a game that will stick around and make it money for a long time.