Hearthstone's game director Ben Brode gave an interview to Ars Technica where he spoke about Blizzard's card game and it turns out that Overwatch's Jeff Kaplan is indirectly responsible for how Hearthstone's fatigue mechanic came to be.
Apparently, Kaplan has visited Hearthstone's headquarters while the game was in an earlier stage, choosing to have a go against the AI. He was winning as well but then he got the "You Lose" message after he ran out of cards.
Apparently, this didn't look one bit, prompting the Hearthstone team to ensure the game recognises a player who has been better throughout the match, even if it does punish running out of cards. Ultimately, the mechanic worked like a charm, Brode says.
Asked what were the craziest ideas for Hearthstone cards, Brode listed a few. For instance, the World Flipper turned the board upside down and a single look is enough to realise it'd be an infuriating experience. Good call Brode, good call.
Another wacky card idea was the Auto Pecker, which would inflict damage to players every time they moused over it. With Hearthstone being as popular as it is though, the devs were worried about people hacking data packets and ultimately abandoned the idea altogether.
Also tried and failed was an ooze that cost three mana and while it had one attack and health, it would gain +1/+1 for every game you've lost in a row.
Brode also revealed that the next Hearthstone set has already completed the final design process, where the team ensure balance, fun and clarity of the cards. Currently undergoing Hearthstone's design process is the set after that, whereas the third set in the initial phase.
He also talked about one of the secrets on Hearthstone boards, such as lining up against the Lich King with Anduin the Priest. Anduin has what Brode calls "the most humiliating" treatment, where the Lich King mutes him.
If you happen to steal or copy the car and mute him back, however, he'll continue speaking in a muffled voice. Apparently, the team recorded a lot of audio footage for such purposes, throwing it all into Hearthstone.