Three and a half years after its release, Hearthstone , Blizzard’s online card game, is showing an insolent health. In an extremely competitive niche ( Magic Online , Gwen, The Elder Scrolls: Legends …), the game claims more than 70 million subscribers, and its ninth extension, Cuckolds and catacombs , is released Friday, December 8th.

“The original idea was to try to replicate a” dungeon crawl ” [the exploration of a dungeon like the table games like Dungeons and Dragons ],  ” says senior game designer Peter Whalen. Hearthstone , visiting Paris in early December. “We started by thinking about the treasures that would be found there: legendary weapons, unknown treasures, potions with weird and unknown effects … We then devised game mechanics faithful to this spirit, and then thought about other ways to make the atmosphere of a role play dungeon, introducing a notion of experience on some cards, the ability to recruit allies … “

Finally, 130 new cards will be added to the nearly 1,000 cards already out, in an extension that mixes a playable adventure solo and classic card packs to win or buy.

Not to discourage new players, several game modes are designed specifically for beginners, others for hard players, and one of them was even thought for players who come back after a long absence. Not to discourage newcomers while satisfying the old is a major issue, notes Ben Thompson, artistic director of the game. “We talk a lot about new players – a designer in the team works full time on their experience, and we analyze all the statistics about them. “

Attention to detail, analysis of statistics and ongoing optimization are part of Hearthstone’s trademark and other Blizzard games. But the balancing of card games, which allow many interactions difficult to predict, is particularly complex – in recent years, Blizzard had to modify after publication the effect of several cards that imbalanced too much the game, relying on statistical analysis, but also to player feedback.

“Some cards cause emotional reactions,” says Peter Whalen. “This was particularly true of Deck ” quest thief “[a type of very popular game and considered very powerful, the main card was changed this year to weaken] . Players who lost to this deck found it unfair – even though our statistics showed that it did not even win 50% of the games! It was not the most played deck either. But when they faced him, the players found him particularly frustrating, and that feeling is also important. A balanced game is not a game where all decks have a 50% chance of winning – it’s just a game that’s fun. “