Hearthstone is a free-to-play online digital collectible card game developed and published by Blizzard Entertainment. Originally subtitled Heroes of Warcraft, Hearthstone builds upon the existing lore of the Warcraft series by using the same elements, characters, and relics. It was first released for Microsoft Windows and macOS in March 2014, with ports for iOS and Android releasing later that year. The game features cross-platform play, allowing players on any supported device to compete with one another, restricted only by geographical region account limits.
The game is a turn-based card game between two opponents, using constructed decks of 30 cards along with a selected hero with a unique power. Players use their limited mana crystals to play abilities or summon minions to attack the opponent, with the goal of destroying the opponent’s hero. Winning matches and completing quests earn in-game gold, rewards in the form of new cards, and other in-game prizes. Players can then buy packs of new cards through gold or microtransactions to customize and improve their decks. The game features several modes of play, including casual and ranked matches, drafted arena battles, and single-player adventures. New content for the game involves the addition of new card sets and gameplay, taking the form of either expansion packs or adventures that reward the player with collectible cards upon completion.
In contrast to other games developed by Blizzard, Hearthstone was an experimental game developed by a smaller team based on the appreciation of collectible card games at the company. The game was designed to avoid pitfalls of other digital collectible card games by eliminating any possible plays from an opponent during a player’s turn and by replicating the feel of a physical card game within the game’s user interface. Many of the concepts as well as art assets were based on those previously published in the physical World of Warcraft Trading Card Game.
The game has been favorably reviewed by critics and has been a success for Blizzard, earning nearly US$40 million per month as of August 2017. As of November 2018, Blizzard has reported more than 100 million Hearthstone players. The game has become popular as an esport, with cash prize tournaments hosted by Blizzard and other organizers.