Hearthstone popularity is a mystery to some. The game is absolutely killing it in the collectible card game market.

According to SuperData, an analyst firm, Blizzard is pulling in $20 million a month from Hearthstone, its digital collectible card game (CCG). While the PC version of Hearthstone used to be the most popular, it’s now being dominated by the mobile version. The mobile version brings in more than $10 million a month.

Hearthstone is free to play, but users can purchase packs of cards to build out their deck. Two packs cost $2.99. Players can also purchase expansions for the single-player mode of the game. And they can buy card backs and skins for their heroes.

SuperData notes that nowadays it’s crucial for brands to thrive on multiple platforms. “…Gamers play on multiple platforms at once, and spread their time and spending accordingly,” says SuperData CEO, Joost van Dreunen.

Hearthstone PC Mobile Users

Hearthstone popularity on mobile platforms, says SuperData, shows that people who play complex games don’t just want them on a dedicated platform like PC or other consoles. They want to be able to access them from anywhere. The firm credits Hearthstone’s popularity to the recognizability of the Warcraft characters and the accessibility of the game. Because of Hearthstone, “Players expect CCGs to let them play across devices and be easy to learn yet tactically deep.

Now there is also a smartphone version of the popular card game Magic: The Gathering, called Magic Duels: Origins. Previously, digital versions of Magic appeared on consoles and tablets, but not on phones. Origins is available on iOS, as well as consoles and PC. It takes some notes from Hearthstone’s tactic of creating a challenging game whose mechanics are still easy to grasp. Magic has long been the quintessential physical CCG, but it’s a hard game to break into.

Hearthstone is certainly a challenging game. But it’s also cleverly designed to lead a first-time player through the basics in a way that’s both fun and addictive. It’s the definition of “easy to play, hard to master.” Evidently that balance has paid off for Blizzard.

This article was written by

Simone de Rochefort is a game journalist, writer, podcast host, and video producer who does a prolific amount of Stuff. You can find her on Twitter @doomquasar, and hear her weekly on tech podcast Rocket, as well as Pixelkin's Gaming With the Moms podcast. With Pixelkin she produces video content and devotes herself to Skylanders with terrifying abandon.