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There are probably better questions to ask the principal game designer of one of the most popular card games ever made. But I wanted to know about Hearthstone's fish puns (see: Anyfin Can Happen).

"I am the instigator of many of the puns on Hearthstone. If you have a Murloc card with a fun name, then I probably named it," said Mike Donais, referring to a race of creatures in the game.

Hearthstone launched in early 2014, exploding to 70 million players in just three years. There were digital card games before and there have been digital card games since, but nothing has quite come close to the critical mass of Blizzard Entertainment's free-to-play collectible card game.

The start of April saw the release of Journey to Un'Goro, the ninth expansion in the game's history and the 10th set of cards overall. It borrows its theme -- like all of Hearthstone -- from World of Warcraft. This time, it's based on the primordial and prehistoric Un'Goro crater. Think dinosaurs, raw elemental power and aggressive adaptation. So with the Murloc jokes aside, it was the perfect time to sit down with Donais to learn how Blizzard's Team 5 keeps Hearthstone evolving.

Donais has the unenviable task of designing and balancing Hearthstone's cards. But for all the spreadsheets and tweaking of numbers, he paints his role in broad strokes.

"The overarching goal always when making design decisions for Hearthstone is: What's gonna be fun?" he said. "If a game is fun, people will play it, people will keep playing it, people will tell their friends to play it. So what is fun?"

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He chalks up that huge playerbase to Hearthstone's simplicity. Not meaning that it's easy to play, just that, crucially, it's easy to understand.

"We design our game with understanding the board at one glance in mind," said Donais. Studying the board for the first time, you can see that simplicity. The health and attack power of your creatures is immediately visible. Any additional abilities are also flagged with specific icons. "We have a very constrained design, but we're rewarded by a much more understandable game."

Those clear fundamentals, honed over the first handful of expansions, gave the design team room to play.

"As the game gets older, we can do more crazy things, right?" He throws back to the first expansion set. Instead of new cards artfully breaking the rules, Curse of Naxxramas built on existing mechanics and themes from the basic set. Befitting the flying necropolis setting, it introduced a small number of cards that had effects that triggered when cards died. Simple, with an in-game precedent. And like the best kinds of game design, it was a marriage of theme and mechanics.

"Whenever we make a new set we talk about what's the fantasy of this set? Well, why would you be in Un'Goro? You're on a quest. Then we said, OK, well what does the quest do? And we started talking about what a quest means and we eventually got to the idea that it's a card in your hand that progresses when you do something special and eventually, you complete the quest and get a reward."

We're just coming to the end of the first monthly competitive season to use cards from Un'Goro. Between the new Quests offering more deck variety than any other expansion from the past year and the new Adapt mechanic, Hearthstone feels like it's in a good place. Or at least, a different place.

Changing the game behind the game

If you're the kind to spend a lot of time thinking about Hearthstone and reading forums (personally guilty), you'll see a lot of complaints about the Hearthstone meta (also guilty). The metagame refers to not just the internal rules of the game, but the kinds of decks people are playing, how favourably your deck matches up against other popular decks.

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The issue with the Hearthstone meta, as so many armchair designers saw it, was that it became increasingly stagnant. A tiny selection of decks were viable, and they weren't fun to play against.

Both the problem and the solution was in data. You don't hit 70 million players without getting a buttload of information about the game, and people talking about it.

"What happened is now people have a lot more correct data about what is best, or almost correct data," says Donais. "Because a lot of people are following the internet more, they're analyzing match ups more. So, once there's a deck that's called the best by something they trust, whether it's right or not, everyone will just start playing that."

But using that data, Donais and the rest of Team 5 can make predictions, run models and playtest changes to cards to preserve the health of the game. Before the release of Un'Goro, there were complaints that some decks were overpowered and that the metagame of Hearthstone had been solved. But Donais points to the meta being self-correcting. That's his reason for Blizzard's famously soft-touch approach to changing existing problem cards.

"We wanted to see what happens with players experimenting on their own and trying to beat certain strategies."

Eventually, people got over it. It happened with the most recent banes of the Hearthstone ranked ladder. The new card releases mean the game changed just enough that they weren't the oppressive powerhouses they once were. Those decks weren't as strong because people weren't necessarily playing stronger decks. Just different ones.

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Where Donais has the most fun is in being surprised.

"We put out tools that we think, this kind of makes sense. We don't know exactly how it's gonna get used. It's sometimes nice to have cards we don't know how they're gonna get used. It leaves it open for the players to figure out how they wanna use them."

Take Hemet, Jungle Hunter, a new card that destroys all the cards in your deck that cost three mana or less. "Hemet is a great card because we have no idea how people are gonna use it."

After around a month of Un'Goro, I'm inclined to agree with Donais. Breaking the rules has been the best thing that happened to the game. It feels fresh for the first time in months, which is the be-all and end-all for a game built on constant releases. That and the puns, of course.

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