Hearthstone: Heroes of Warcraft is an online collectible card game developed by Blizzard Entertainment. It is free-to-play withoptional purchases to acquire additional cards and access content quicker. The game was announced at the Penny Arcade Expo in March 2013 and released on March 11, 2014. Hearthstone is available on Microsoft Windows and OS X systems and on Windows 8,iOS and Android touchscreen devices. New content for the game involves the addition of new card sets and gameplay, such as from the Goblins vs. Gnomes expansion pack and the Blackrock Mountain adventure.

In early May 2015, there were more than 30 million registered Hearthstone accounts.

Cards:

In the card interface, players can create and edit their decks from existing cards, as well as 'disenchanting' and creating new cards.

Cards are the main substance of Hearthstone, representing the abilities, characters and effects which each player is able to make use of during the match. There are 566 collectible cards in the game, with more planned to be added in the future through additional expansion packs and adventures.The first adventure, Curse of Naxxramas, added 30 cards. The first expansion, Goblins vs. Gnomes (GvG), added 123 cards. The second adventure, Blackrock Mountain (BRM), added 31 cards.

 

Gameplay:

Hearthstone is a digital collectible card game that revolves around turn-based matches between two opponents, operated through Blizzard's Battle.net.Players can choose from a number of game modes, with each offering a slightly different experience. Players start the game with a substantial collection of basic cards, but can gain rarer and more powerful cards through purchasing packs of cards or as reward for completing Arena runs. In-game gold is rewarded for completing randomized daily quests, where one is given each day stacking up to three (one quest is able to be rerolled per day), and by winning matches in ranked play, where 10 gold per three wins is earned with a 100 gold limit per day.

(From Wikipedia)