On the set of ITV’s costume drama Mr Selfridge, in a quiet moment between takes, actor Greg Austin is a world away from his co-stars. Although dressed as an Edwardian gentlemen, he is glued to his iPhone, and to one game in particular. Hearthstone.

“I got into it somewhat late, about a year after its release,” he says. “But since then I’ve been playing avidly. It is easy to learn, which means anyone can play it and enjoy themselves, but it is also difficult to master.” Austin loves the game so much, he now has his own dedicated YouTube gaming channel, EuphAuric, posting regular Hearthstone videos.

He is not alone with this obsession. A year after its release on PC and iPad, Hearthstone boasts over 30 million registered players, and together with online shooter Destiny, drew in $850m (£540m) of revenue for Activision last year. It is one of the most watched titles on the video game streaming site Twitch, and professional gamers can earn tens of thousands of pounds in dedicated tournaments. One reviewer for influential US games site Polygon wrote simply: “It’s kept me rapt longer than any games I’ve played in years.”

A Priest takes on a Paladin in this Heathstone match. The Hero characters are at the top and bottom of the screen with the minions meeting in the middle of the board. Photograph: Activision

For those yet to be indoctrinated, Hearthstone is a turn-based strategy game based in an esoteric fantasy universe and inspired by complex collectible trading card sets like Magic: The Gathering. Players select one of nine character classes such as hunters, warriors and priests, then build decks of soldiers called Minions, each with their own abilities and weaknesses. These mini armies are pitched against an opponent on a table-top warzone, with a resource named mana governing how many cards a participant is able to play in their turn. The aim is to destroy your opponent’s main Hero character by playing stronger Minion cards at the right times, and making effective use of special spell cards that add force to compatible moves.

It sounds complicated and geeky, which is perhaps why so many industry insiders were caught off guard by its sudden and phenomenal success – including, it turns out, the game’s own developer. To Blizzard Entertainment, Hearthstone was supposed to be a niche project, an experimental diversion. But then something weird happened. Everybody loved it.

The Blizzard way

Based in a sprawling campus facility in Irvine, California, Blizzard is the veteran studio behind acclaimed strategy simulation titles Starcraft and Warcraft, and the massively multiplayer online game, World of Warcraft (WoW). Its games are the very definition of “hardcore”: deep, demanding and riddled with complex mechanics. In 2008, however, the company’s directors looked at how they were relying exclusively on three key brands – the action role-playing adventure Diablo, the strategy simulation sequel Starcraft II, and WoW – and they were concerned. In some ways it was fine, the games were, after all, doing spectacularly well. Starcraft was about to get its Wings of Liberty add-on and work was progressing on the long-awaited Diablo III.

Elsewhere, however, something big was happening in the games industry. A group of idiosyncratic independent projects like Braid and World of Goo had kickstarted a new era of experimental game design. The arrival of digital download platforms like Xbox Live and the Apple App Store, together with the increasing availability of broadband internet, meant that suddenly small teams were able to get interesting offbeat projects to potentially huge audiences. Games didn’t have to be burned onto discs and sold in stores anymore, they could be created by small teams then made available on the internet or on smartphones. The culture of the industry was shifting. Blizzard wanted to shift too.

“We realised we didn’t have a competency here at the company to be a little bit more experimental, a little more nimble,” recalls Hearthstone co-creator and production director, Jason Chayes. “Some of our executives got together and said, we need to start up a small team, kind of a scrappy team, that can, with few resources, find ways to do more experimental types of games. We wanted to try out different ideas and platforms – things we don’t usually do because our teams are focused on those key franchises.”

The studio pulled a small group of experienced designers together, including Jason Chayes and designer Eric Dodds, and gave them the codename Team Five. The brief was effectively, go create something. “We started where we always do, by asking each other about the games we really love ,” says Chayes. “We discussed the games we played in our lunch breaks or with our friends in a pub on a Friday evening. For about twenty years, a lot of us had been playing collectible card games (CCGs) together. The coupling of a small team and an online CCG felt like a natural fit. That’s where Hearthstone began.”



A magic gathering

Although there have been trading cards with simple gaming mechanics for many years, it was the 1993 release of Magic: The Gathering that revolutinised the CCG concept. Published by veteran fantasy game creator Wizards of the Coast, and set in a Dungeons and Dragons-style fantasy world, it featured a starter pack of creature, spell and artifact cards all with different strengths and weaknesses, as well as random booster packs allowing players to build their own custom decks. Part of the fun was simply purchasing packs and amassing a collection, enjoying the exotic creature descriptions and fantasy art. But being able to sit down and play a highly tactical game added to the appeal. Magic became a smash hit, selling out its initial 2.6m print run almost immediately and going on to build a community of over 10m active players. It wasn’t long before it earned the nickname cardboard crack.

Team Five was looking into what made a compelling collectible card game – and that meant playing them. A lot of them. They played endless rounds of Magic, as well as subsequent CCG hits – Battletech, Netrunner, Legend of the Five Rings and Rage – learning the flow, the interplay, the conventions of the genre. “We thought, well, what does a card game need to give it interesting depth?” says Chayes. “We wanted a style of play where minions could duke it out against each other – a very quick, dynamic engaging experience. There was a process of working out what sort of things would facilitate that form of gameplay.”

Hearthstone’s Tavern Brawl mode. Photograph: Blizzard

And of course, they borrowed from the World of Warcraft card trading game produced by Upper Deck in 2006. This hugely successful spin-off from Blizzard’s massively multiplayer online game was a massive success on the CCG market, with over 20 expansion sets and a lively competitive scene. It has similar hero classes, it duplicates a lot of the minion cards, and card art, and many of the systems are the same. And when Hearthstone was nearing completion, Blizzard ended its licensing agreement with Upper Deck, effectively killing the physical Warcraft card game in favour of its digital counterpart.

But Team Five was also looking back to the origin of the Warcraft titles and its universe, the dark fantasy realm known as Azeroth, swarming with warriors, elves and orcs. As Chayes explains, “We thought about the various classes that are represented there – hunter, mage, paladin, all of these – and discussed what it is that people think about when they consider what a paladin is, the buffs they may use, or the burst energy spell of a mage. We looked for ways to introduce those mechanics into a card game. That was a key influence: how we could be faithful to that source material?”

The Starcraft experience

A year after work started, the team had developed a simple Flash prototype – a very basic digital card game with no real visual identity; it was just a set of mechanics, based around the nine classes of hero from the Warcraft real-time strategy titles. At this critical point, several of the staff were temporarily moved on to Starcraft II – and far from being a disruption, this proved an important element in Hearthstone’s development. “There were 10 or 11 months where the two people on the design team – Eric Dodds and Ben Brode – were free to do a lot of fast iteration,” says Chayes. “They were actually making and using physical playing cards.”



Meanwhile, the others learned a lot from Starcraft, especially the asymmetric nature of the races. “That definitely carried over into Hearthstone,” says Chayes. “The idea that each of the classes needs to remain balanced but at the same time has to have its own flavour and feel. When the team started reconverging, having done our tour of duty on Starcraft, that’s when things started to migrate into a very robust example of where we wanted Hearthstone to go.”

Behind it all were two guiding principles: accessibility and charm. It had to be funny, it had to be warm and it had to be intuitive. “When we first started working on it, the most important thing was that this would be a game for everybody,” says Dodds. “That idea quickly spread throughout the entire game. We wanted to make it feel good to drag cards, to attack, we wanted it to look fun if you just watched it over someone’s shoulder.

“We talked about the text on the cards - we wanted to make it very readable. We have a rule when we’re building a card that if someone reads the text for the first time and they don’t immediately understand what the card does, we need to change that power or re-word it – that is critical.”

Indeed, the game is so intuitive, players are able to effectively let it play itself. There are pre-built card decks for each class so players don’t have to make their own. But if they do decide to make custom decks, the game will make suggestions, or even build the whole deck based on the cards available. Then, when you’re in the game, the user interface highlights all the cards that you can play in any one turn. As with casual puzzle titles like Candy Crush Saga, you can just do what the game tells you.

“It’s very apparent that Blizzard wanted the game to be quick, and reasonably easy,” says keen player and eSports writer, Kevin Hovdestad. “Turns are short, games are short, and you can’t act in any way during your opponent’s turn. Strategically, each class has inherently valuable cards that fit it thematically, so the game sort-of guides players towards certain natural synergies.”

Dodds agrees. “It’s important that you don’t have to spend a lot of time understanding the rules to play the game, the depth grows as you go,” he says. “A number of players will just drag the card that goes green onto the board – they’re sort of playing the game, sort of not. But as they progress they start to think, ‘no, I’m going to play a different way’.

“Really, throughout the design, the interface, the experience, Hearthstone is designed to say ‘the first time you see this, you know how to play, you know how to use it’”.

Meanwhile, back on the set of Mr Selfridge, Austin regularly finds himself showing off the game to other cast members as they mill about on set. For him, performance is part of its appeal. “It is extremely watchable,” he says. “The other actors are always asking what I’m doing, and I’ll tell them about the game and get them to have a go. That’s how I really started to learn the finer details – by watching popular streamers and YouTubers like Trump and Kripparian. There’s always more to learn and understand with Hearthstone, and watching other people is one of the best ways of getting better. I wouldn’t be surprised if I’ve managed to get a few of the other actors into it.”

Part Two: the design process, and how Hearthstone evolved into an eSport