Hearthstone – Overwatch -: Heroes of Warcraft - Blizzard Entertainment – Directors Ben Brode, Jason Chayes & Eric Dodds - Designers Derek Sakamoto & Mike Donais - Microsoft Windows – PlayStation 4 – Xbox One X – Xbox One– Activision – Esports - Overwatch League – Warcraft – Unity – Unity Engine - World of Warcraft Trading Card Game – Gamescom – E3 – Tokyo Game Show – Brazil Game Show The game is a turn-based card game between two opponents, using constructed decks of thirty cards along with a selected hero with a unique power. Players use their limited mana crystals to cast spells or summon minions to attack the opponent, with the goal to reduce the opponent's health to zero. Winning matches can 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, as well as daily quests to help players earn gold and cards. New content for the game involves the addition of new card sets and gameplay, taking the form of either expansion packs or single-player 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. As of May 2017, Blizzard has reported more than 70 million Hearthstone players. The game has become popular as an eSport, with cash prize tournaments hosted by Blizzard and other organizers.