Curse of Naxxramas: A Hearthstone Adventure will be the first-ever expansion for Blizzard's free-to-play digital card game, featuring 30 new cards, a new game board and single-player class challenges.

The expansion takes the form of a card-based dungeon crawler, with five "wings" unlocking over as many weeks simultaneously on all platforms. Each will feature new single-player encounters with boss fights and unique cards. The first wing, The Arachnid Quarter, will be available for free to all Hearthstone players at launch. The remaining content, true to the game's free-to-play model, will be available either with real money orin-game gold.