Hearthstone is one of iPad’s highest-grossing apps in its soft-launch territories

It’s just a digital card game, but Hearthstone: Heroes of Warcraft is quickly turning into Blizzard’s money-printing machine.

The collectible-card battler finally debuted to the public on PC and Mac earlier this year. And then on April 2, Blizzard released the free-to-play Hearthstone for iPad in Canada, Australia, and New Zealand. The mobile version has quickly shot up the most-downloaded charts in those territories, and it’s also enabled analysts and industry observers to see if fans are spending money. Turns out that they definitely are.

Hearthstone is the ninth highest-grossing app on iPad in Canada right now. On that same chart in New Zealand and Australia it is 11th and 12th, respectively. This is after less than 10 days of availability, which suggests that the game is quickly converting mobile players into paying customers. While Hearthstone is free to download, it charges gamers money for packs of cards or to enter its Arena mode, which could also net players more virtual goods. The studio also today announced that it will introduce a single-player quest that will charge an entrance fee. Of course, players can use in-game gold they get from completing challenges to pay those tolls, but Hearthstone’s performance on the iPad charts suggests many are happily spending real-word cash.

Hearthstone players on mobile aren’t just spending 99 cents at a time, either. Here are the top five in-app purchases, according to iTunes:

1. $10: Bundle of seven expert packs of cards
2. $3: Bundle of two expert packs
3. $20: Bundle of 15 expert packs
4. $2: Arena admission
5. $50: Bundle of 40 expert packs

This hot start has some industry analysts not only feeling optimistic about the game but also about publisher Activision Blizzard as a whole. Analyst Doug Creutz, of investment firm Cowen & Company, raised his price target for Activision (the price that would be best to sell an $ATVI stock at) from $21 to $23 in large part due to the performance of Hearthstone.

“We are raising our fiscal-year 2014 revenue estimate for Blizzard’s digital collectible-card game [Hearthstone] from $100 million to $150 million on strong initial results from the iPad beta testing in Canada and Australia,” wrote Creutz.

In what he calls an “upside scenario,” Creutz believes that Hearthstone and the upcoming free-to-play multiplayer battler Heroes of the Storm could generate more than $200 million in revenue in 2014.

Hearthstone is still only available on mobile in Canada, Australia, and New Zealand. Blizzard has not announced when fans can expect the worldwide release. The company also has Android and iPhone versions of the card game in the works. That release is expected later this year.