Hearthstone is a digital battle card game set in the WarCraft universe from Blizzard Entertainment.
You can select one of 9 heroes in the WarCraft universe, each with their own single hero ability, hero-specific cards and available-to-all-heroes neutral cards to battle other players in a random-but-fair matchup on Blizzard's own Battle.net to earn more cards and raise your ranks among other players.
Hearthstone will be free-to-play with random card packs available for real-money purchase. Though this might discourage some players, the game matches you up with opponents of closely identical deck (card value wise).
ALL cards can be bought with in-game gold which is earned by completing daily quests, winning a set amount of games and playing Arena mode. Furthermore, all cards in your collection can be broken down into "Arcane Dust", a form of material to create ANY card in the game.
Hearthstone is designed to streamline the tcg (trading card game) formula to provide equal parts fun and challenge to players of all levels. This is the current to-go entry-level battle card game for novice players.
The game was announced at Penny Arcade Expo, March 2013 and entered closed-beta in August 2013. Open-beta will begin from December 2013.
Hearthstone will be available for PC, Mac (currently available for closed-beta) and iPad. iPhone and Android version are expected Q4 2014.

When you've played too much Hearthstone; and you need to stop, but you can't.

The phrase "Hearthstoned" is used mainly in card games other than Hearthstone, used to describe the sheer fool you've made out of your opponent through the abuse of RNG}. When you are Hearthstoned, you are obligated to either mask your face in shame or to slowly walk out of an enclosed territory you're currently occupying.
Often times Hearthstoning an opponent could lead to spontaneous orgasms, tensing of muscles, and the reference of oneself as a "legend."

The type of nerd who sits alone at home playing hearthstone because they would rather play with digital cards than real ones. The will, most of the time, not smash raw.

Whenever Swagsplif goes live for any length of time.