Blizzard Entertainment developed and produced Hearthstone, a free-to-play online digital collectible card game. Hearthstone, formerly known as Heroes of Warcraft, draws on the existing lore of the Warcraft series by employing the same concepts, characters, and treasures. It was first launched in March 2014 for Microsoft Windows and macOS, with iOS and Android adaptations following later that year. The game supports cross-platform play, allowing users to compete on any compatible device, with the sole limitation being geographical region account constraints.

The game is a turn-based card game played between two opponents utilizing 30 card decks and a chosen hero with a special ability. Players use their limited mana crystals to call minions or use skills to assault the opponent’s hero, all with the objective of eliminating the opponent’s hero. Winning matches and completing objectives will award you with in-game gold, new cards, and other goodies. Players can then personalize and strengthen their decks by purchasing packs of additional cards with money or microtransactions. Casual and ranked matches, drafted arena fights, and single-player adventures are among the game’s forms of play. The game’s content consists of new card sets and gameplay, which are delivered in the form of expansion packs or adventures that reward the player with collector cards upon completion.

Hearthstone was an experimental game built by a smaller team focused on the company’s enjoyment of collectible card games, in contrast to other Blizzard games. By eliminating any possible opponent plays during a player’s turn and duplicating the feel of a physical card game within the game’s user interface, the game was meant to avoid the flaws of existing digital collectible card games. Many of the concepts and visual elements were inspired by those seen in the real World of Warcraft Trading Card Game.

The game has received positive reviews from critics and has been a financial success for Blizzard, with monthly revenues of almost US$40 million as of August 2017. Blizzard reported more than 100 million Hearthstone players as of November 2018. The game has grown in popularity as an esport, with Blizzard and other organizers hosting cash prize competitions.