It turns out Jeff Kaplan from the Overwatch team inspired Hearthstone's fatigue mechanic.
In a fun video interview with Ars Technica, Hearthstone game director Ben Brode reveals how Blizzard came up with the fatigue mechanic, which deals an increasing amount of damage with each turn a player has no cards left to draw from.
"We were doing a play test, and we asked Jeff Kaplan, who's the game director on the Overwatch team, to come over and try the game," Brode begins.
"And, he got really into it. He started playing minions, and attacking, and he was having some fun figuring out what cards to play, and he had never played it before, he was excited to get into it.
"And, he was very close to winning, and then, the computer he was playing against passed the turn. It said, 'Your Turn,' 'You Lose.' And, what had happened was, he'd run out of cards. Traditionally, in a lot of these card games, when you run out of cards, you lose, 'cause, what else can you do? And, it was such a stark moment. It made the whole game feel completely useless, because it didn't matter the decisions he made during the game, he was just going to lose as soon as he ran out of cards anyway.
"And so we said, 'Hey, after watching Kaplan have that experience, we need a different solution for running out of cards. And so, we designed the fatigue mechanic, where it ratchets up the damage every time you try and draw a card but your deck is empty, you starting doing one, then two, then three, then four, it increases over time how much damage you take.
"What that does is, it connects back in with the whole rest of the game that's happened before it. If you were one damage away from killing your opponent, he's going to die to fatigue.
"So, that whole game where you got him to that point mattered a lot. If you have a huge amount of minions, you have time to attack and deal the damage you need to to kill your opponent. The game matters again. It isn't a huge surprise and moment when you run out of cards. It slowly ramps up to let you know, 'Hey, this game will end. 'You do need to get it going.' But, it isn't breaking you out of that gameplay experience."
So there you have it: the story behind Hearthstone's fatigue mechanic involves Jeff Kaplan from the Overwatch team. Clearly, everything our Jeff touches turns to gold.
The rest of the video interview is well worth a watch, by the way. It's a lot of fun, informative and entertaining. I particularly liked the bit about the cards Blizzard came up with but ditched because they were too crazy. One turned the game board upside down!