Blizzard announced Hearthstone in the opening minutes of the convention. The game is being developed by a new, smaller team at the studio that wanted more freedom to experiment and create quicker titles.
Hearthstone is a free-to-play title that will pit players against each other over an animated 3-D table with nine classes from World of Warcraft. It will use Battle.net matchmaking to pair up users.
Packs of five cards (with varying degrees of rarity) can be either earned through playing the game or purchased separately. The team wanted to make the game intuitive and simple to play, as well as dynamic and exciting to watch. Duplicate cards can be disenchanted to create new cards as well.
You can watch the trailer after the jump.
[Update: To be clear, the cards are earned through Hearthstone play, not WoW play.]