I'm over Twitch Plays Pokemon, but it was fun while it lasted for me. And that's not to say I'm bored of the concept of people collaborating to play a game via live stream, generally speaking. Some will be hits, some will be misses. I'm not yet sure where Hearthstone: Heroes of Warcraft falls.
Find out for yourself at Hearthmind. Players can drag their mouse cursor directly on-screen to "vote" for an in-game action during a five-second window, and the winning move will be performed after a small delay. Super easy to get into, but that's not saying much when you have so many people trying to pull off competing strategies. And the aspect of Twitch Plays Pokemon I most enjoyed -- the hilarious, creative lore -- seems less likely to happen here.
I watched one full round that unsurprisingly ended in defeat. To quote someone in chat, "this machine dont pay attention to the clicks just end turs like a insane."