Hearthstone: Heroes Of Warcraft has been available on PC since March 2014 and out on tablets since April 2014 and had reached 25 million users by January of this year. That wasn't enough for Blizzard, and it's just released a smartphone version of the game that is even compatible with the iPhone 4s's diminutive screen.
As it was announced the game now has 30 million players, Blizzard's Jason Chayes (production director) and Eric Dodds (game director) spoke to GamesIndustry.biz about some of the challenges and priorities that shaped the title's latest incarnation.
"When we first started on the game we didn't have plans to do a phone version, for that matter we didn't plan to do a tablet version when we first started," admits Chayes.
Eventually the team decided a phone version was something they were excited to work on, and began research and development. Unlike the PC version, the team had to rely on internal feedback for their beta process.
"Because of the way the distribution is set up through Apple there isn't really a good beta process where we can roll out the phone build to our community," continues Chayes.
"We'd love to be able to do that, there's just not really a good facility to be able to do that right now so in this case we really had to kind of rely on our company to give us the feedback and act as a proxy for the various types of people who play mobile games out there - the hardcore players and the more casual players - and really kind of get as much of that as we could before we went out to the world with it."
The obstacles the team really had to tackle when it came to the smartphone version was a UI that would work on smaller screens, making sure smartphone players got the full Hearthstone experience and the slightly less reliable nature of player connections.
"The games are pretty short so it lends itself pretty well to those shorter bursts of playing on a mobile device, so overall I would say we didn't really change the basic fundamentals of the game in terms of what it means to play a match," he explains.
Hearthstone on smartphone also features a handy indicator in the UI so players can be on alert if their failing phone signal is about to sabotage their big win.
"We know we're not going to have as much control on the game side about what are people doing as they're kind of moving into and out of different cell signals or jumping in and out of wifi, so one of the things we did put a lot of time into to kind of bolster the player experience around that is to try and make the reconnect experience as quick and as efficient as we possibly could."
Dodds is especially pleased with how the new mobility has enabled more players to take advantage of the game's Fireside Gatherings feature, which allows players in the same place to play together.
"As funny as it sounds we're actually really excited about people playing this digital game in the same physical space together," he says.
"With a mobile it just makes it super easy for you to show up at one of these locations and you've got the game in your pocket so it's actually had some sort of side benefits in that way."
"As funny as it sounds we're actually really excited about people playing this digital game in the same physical space together"
Blizzard expected already committed players to grab the chance to play on their phones, but Chayes said they've also been pleased at the number of new players the port has attracted.
"We've definitely seen a lot more people picking up the game, and brand new players who are playing Hearthstone for the first time," he says.
We imagined that a lot of existing Hearthstone players would go and download the app but one of the things we've been very pleasantly surprised with is just how many players are playing Hearthstone for the first time. We're seeing that across both iOS and Android so it's definitely picking up some good steam there and we're excited to see it continue to grow in the months to come."
Dodds is quick to point out that this move to smartphone doesn't represent some seismic shift for Blizzard, but reflects the company's flexibility when it comes to the right games on the right platforms.
"it actually goes back to whenever we're making a game we look at the game and we go would this game be a great fit for some specific platform like we're working on Diablo III and went 'hey Diablo III would be a great fit on console' and they went through that process and we did the same thing Hearthstone and went wow, this would be a really great fit for phones," he says.
"I don't think it's really indicating a shift in our general strategy, it's more that we looked at this game and felt like it would be a great fit on phones going forward and so whenever we're making a game now or in the future we're going to be looking and going what's the great platform, or the great platforms, for this game to be on?"
The release on smartphone actually marks the end of a long, very long, initial development phase for the game, and Chayes reveals that now the game is on all the targeted platform the focus has switched to new features and content.
"One of the things that is exciting is that now that we are on phones so we can move some of our team resources back to helping us think about feature releases and upcoming content releases, it definitely is great to have everyone kind of unified to move forward with that stuff.
"You can expect to see more releases like we've done, we have plans to do more expansions and other card releases coming up, but there's also a bunch of features that we've been thinking about for a while and we're excited to get more resources against those."
I ask about an offline mode for the game, a feature which is often requested by community members, especially those who'd like to Innkeeper their way through international flights.
"I wouldn't say it's completely off the table and it is something we've talked about a fair bit. The biggest challenge we have is just that because we are a client server game a lot of the logic for just playing the game resides on the server," explains Chayes.
"So far it hasn't been the leading thing which is why we haven't put as much energy behind it but if that continues as a 'this would really make the game better' then we'll be listening."
"Our balance designers are in touch with some of the top players"
And listening is something the Blizzard team does a lot. Both Dodds and Chayes are delighted at being able to hear directly from the community and to watch people playing their game in real time on Twitch. They even work closely with some of the biggest players.
"Actually our balance designers are in touch with some of the top players and they're always talking back and forth about what some of the top decks might be," says Dodds.
"We're watching them play on Twitch, we of course behind the scenes can look at the metrics and see what the actual numbers are between, the stats on all of those top decks, so we're certainly engaging with our top players across a whole bunch of different ways of connecting."
It's a sentiment that Chayes echoes, even as he describes the strange sensation of watching Dodds on stage, and then watching one of the tops streamers on Twitch also watching Dodds and commenting on the Blackrock Mountain announcement.
"More than at any point - certainly in my career - having a conversation and a dialogue about what it's going to take to make the game better has really been a factor in us doing our prioritisation about what we should be looking at. So we're definitely listening."