Unleash the hounds: Hearthstone was the 12th highest-grossing iPad game worldwide in April

Mobile gamers have already turned Blizzard’s first iPad game into a big hit.

Hearthstone: Heroes of Warcraft, the collectible card game that has players facing off against one another in head-to-head battles, was the 12th highest-grossing app for Apple’s tablet device last month worldwide, according to industry-tracking firm Distimo. That’s despite the game only debuting globally on April 16. While the U.S. was the top-spending country for the card battler, it is really an international success. Hearthstone not only represents Blizzard’s first foray into mobile but also into the free-to-play business model, and it’s already paying off.

Blizzard can thank countries like China and the United States for Hearthstone’s success. From April 16 to April 30, China represented 29 percent of all Hearthstone downloads on iPad while the U.S. made up 24.8 percent. Nations such as Russia, the U.K., France, and Germany were also big into the game, although not nearly as much as the top two.

Hearthstone debuted on PC in late 2013.

In terms of revenue, the U.S. was the leading region by far. The Americans represented more than 35 percent of all the spending in Hearthstone on iPad. China, with 10.5 percent, was No.2, followed by the U.K., Russia, and Australia. The card battler makes money by charging players for new decks of cards (which they can also earn with in-game currency) as well as for entrance into a special Arena mode that reward players with virtual goods.

While things are looking good for Blizzard and its card game, it’s important to note that Japan was not in the top 10 for either Hearthstone downloads or revenue. That’s primarily because Hearthstone is only in English in that important region, which is the No. 2 top-spending country on mobile games behind only the U.S. Blizzard could see a major boost to its revenues if it can get a foothold in Japan.

In addition to expanding to new regions, Blizzard also still has to get Hearthstone on iPhone and Android devices. Those versions are definitely in the works and will likely debut later this year.

Blizzard also plans to update Hearthstone with a new add-on pack called Curse of Naxxramas that will introduce a single-player adventure mode and 30 new cards.

Hearthstone wasn’t the only long-awaited mobile release of an established PC property. Social-game developer Zynga launched FarmVille 2 on Android and iOS on April 17, but it failed to crack the 15 top-grossing game on iPad in April.