Hearthstone is a digital-only collectible card game that revolves around turn-based matches between two opponents using pre-made decks of cards. Players can choose from a number of game modes, with each offering a slightly different experience. Players start the game with a limited collection of basic cards but can gain rarer and more powerful cards through purchasing packs of cards or as rewards from specific game modes. Hearthstone is purposely designed to exclude card trading, while allowing players to disenchant unwanted cards into a quantity of arcane dust that can then be used to craft new cards of the player's choice. Players customize their decks with any gained cards to improve their chances of winning and gaining further rewards.Hearthstone is free-to-play, only requiring the player to download the game client for their computer or device after setting up a free Battle.net account; supporting the ongoing development of the game comes from micropayments. Players can earn in-game gold by winning play mode matches and completing daily quests, such as winning a certain number of matches while in play mode with a particular hero class. A player can have up to three active daily quests which carry over until completed or the quest is declined by the player then a new daily quest is given once a day. Gold can be used for booster packs, entry tickets for arena and access to adventure wings. Alternatively, players can spend real money to purchase these items directly, and can buy exclusive card back skins and alternate heroes. During the week before the Journey to Un'Goro expansion released in April 2017, Blizzard temporarily added daily log-in rewards that included gold, arcane dust for card crafting, card packs, and individual cards. Hearthstone is set within the Warcraft universe, with its characters, spells and locations drawing mostly from existing lore. The game has a few original characters like Sir Finley Mrrgglton and Morgl that were later added to World of Warcraft.

Game modes

Five game modes are available to play in Hearthstone. Matches in all modes except for Solo Adventures count towards quest completion; Duels initially did not count towards quest completion except during limited periods, but a game update in June 2017 allowed these matches to add another way to complete the daily quests.

- Play mode allows players to match up against human opponents of similar skill. Players can choose to play casual 'friendly' games, or take part in the ranked play system, earning ranks to reflect their skill and standing within the community over month-long seasons. Ranked play features two separate tiers: 25-1, and Legend

- Solo Adventures are single-player modes against computer-controlled opponents that are either Practice matches or Adventures. In Practice mode, players can learn the basics of the game against easier opponents that only use basic cards in their decks, or more difficult ('expert') opponents that use a larger pool of cards. Players can also choose which class to play against. In Adventure mode, the player attempts to defeat bosses to unlock new cards.

-Arena mode allows the player to select one of three random heroes and draft a deck of 30 cards by choosing between three random cards at a time. Players use their drafted deck to compete in a series of games against other arena players, generally matched against decks with an equivalent win-loss record.

-Tavern Brawl mode features one-on-one matches with another player. These commonly are competitive matches to defeat the other player, but some matches have featured cooperative goals such as jointly defeating a powerful minion.

-Duels mode also referred to as "Friendly Play" and "Friendly Challenge", allow players to challenge friends on their Battle.net friends list in unranked matches

Matches

Each Hearthstone match is a one-versus-one battle between two opponents. Gameplay in Hearthstone is turn-based, with players taking turns to play cards from their hand, limited by available mana, that include casting spells, equipping weapons, summoning minions to do battle on their behalf or replacing a player's chosen hero with a Death Knight hero. Games may be between two players, or one player and one computer-controlled opponent.

Card categories

Cards are the main substance of Hearthstone, representing the abilities, characters and effects which each player is able to make use of during the match. Cards fall into four broad categories: summon cards to bring minions into the game, spell cards that create some type of immediate effect, equipable weapons that enable the hero character to attack directly and hero cards that transform the basic hero into a different one. All cards have a mana cost that must be provided by the available mana the player has for that turn.
Once summoned, minion cards each have an attack and a health value; when a minion attacks a target, it will deal its attack value to that target's health, and if it is attacking a minion, it will take damage based on the defending minion's attack value. A minion's health does not regenerate at the start of the player's next turn, so minions can be destroyed after taking smaller amounts of damage over several turns. Minions normally cannot attack the turn they are put into play, and once in play can only attack once per turn. Some keywords affect the behavior of minions from these basic rules: examples include those with "Taunt" that must be destroyed before any other minion without taunt or the opposing hero can be attacked, and those with "Charge" can attack the turn they are brought into play. Other keywords define actions to be taken at specific events: minions may have "Battlecry" events that only trigger when they are summoned into play, "Deathrattle" events that occur when the minion is killed, and many more. Tooltips are provided for all keywords, with interactions of minions and their keywords often crucial to success in matches.

Card library and crafting

In the collection interface, players can create and edit their decks from existing cards, as well as 'disenchant' and create new cards.On release, the game consisted of the same Basic set of cards that all players begin with and earn through leveling up all the individual heroes. All additional cards are generally gained by winning or buying card packs in the game; each card pack consists of five random cards. On Hearthstone's release, purchased cards and packs would be from the Classic set, while with the release of each expansion or adventure, cards and packs from that expansion could also be gained

Each player is represented by a 'hero', a character from Warcraft lore representing one of nine specific classes

• Mage
• Hunter
• Shaman
• Warrior
• Warlock
• Priest
• Paladin
• Druid
• Rogue

Decks In all game modes except Arena, some parts of Adventure mode and a few of the weekly Tavern Brawls, the player does battle using a constructed deck of 30 cards selected from the player's collection, using a mix of neutral cards available to all classes and specific class-based cards available to the chosen Hero. Each deck can only feature two of each card and only one of each Legendary rarity card. Legendary cards are the rarest cards in Hearthstone and are usually based on unique characters within the Warcraft universe. Arena play features no such limitations on the number of regular or Legendary cards but requires players to play using a new deck chosen from a series of randomly generated selections.After release, Blizzard has adopted a "Year" moniker to identify when expansions have been retired from Standard format; the first, "Year of the Kraken", lasting from April 2016 to March 2017, retired the "Curse of Naxxramas" and "Goblins vs. Gnomes" expansions, while the "Year of the Mammoth", starting in April 2017, retired the "Blackrock Mountain", "The Grand Tournament" and "League of Explorers" sets. The "Year of the Mammoth" Standard set also moved some Classic cards to the "Hall of Fame" set that is not playable in Standard but still can be obtained through card drops and available to play in Wild format. Since the introduction of the "Year of the Kraken", decks are built either to the Standard or Wild format, and such decks can only be played against a deck of the same format. Wild format decks can use any cards within the Hearthstone library, limited by standard deck construction rules. Alternatively, the Standard format limits cards to those in the Basic and Classic set, and from any newer expansions (those released from a year to two years prior). Cards from previous expansions cannot be used except in Wild formats, nor could card packs or these expansions be purchased, though players could still craft these cards or complete purchased adventures to own them. The Standard approach was added to help improve competitiveness for new players while helping to maintain a dynamic metagame. The construction of a player's deck is a key strategic element in the game, determining which cards are available during a match. The game gives each player a premade deck for each Hero using the game's Basic cards, allowing them to get a quick start in the game. The game provides a few deck recipes for each hero that are based on various successful deck archetypes and it populates the deck with the cards a player already owns. Hearthstone offers a deck construction helper to guide new players on selecting a good range of card types and values, or to finish off decks that are partially completed. The player has the ability to create up to eighteen custom decks, increased from the nine initially available before the release of the Whispers of the Old Gods expansion. With a June 2017 patch, players can share the composition of their deck with others via a unique code generated in-game.

Curse of Naxxramas

The adventure "Curse of Naxxramas" was announced on April 11, 2014, and then was released on July 22. It includes 15 bosses and nine class challenges that together awards 30 cards, which includes six legendaries, and an exclusive card back if all heroic bosses are defeated. "Curse of Naxxramas" was developed to focus on a specific gameplay mechanic, with the team settling onto exploring the design space around the "deathrattle" keyword. This led to the narrative of the player having to explore a location filled with ghosts and undead creatures as to take advantage of deathrattle effects. Since it was a single-player adventure, the team also developed bosses that would be far different from typical human opponents, including some boss characters that would break the fundamental rules of the game. Lead artist Ben Thompson said that they made it felt like winning against these bosses was something that the player earned, as well as helping the player to learn new tricks they could use in regular play modes.

Goblins vs. Gnomes

The expansion "Goblins vs. Gnomes", was announced at BlizzCon on November 7, 2014, and then it was released on December 8. The expansion includes 123 cards found in its specific card pack. Pricing for the packs are the same as Classic packs. "Goblins vs Gnomes" was the first large expansion, and rather than roll out cards as they did with "Curse of Naxxramas", they felt their goal with this "was ‘let’s make a bunch of cards that will really go in and just blow up the meta all at once,’ and we’ll see how it goes, and maybe that’ll affect how we do things in the future," according to Chu. A central theme was designed around the "Mech" tribe cards that would interact with cards that represent goblins and gnomes.

Blackrock MountainThe adventure "Blackrock Mountain" was announced at Pax East on March 6, 2015 and the first wing was released on April 2; the other four wings were opened weekly thereafter. It includes 17 bosses and nine class challenges that together awards 31 cards, which includes five Legendary cards, and an exclusive card back if all heroic bosses are defeated. "Blackrock Mountain" was designed as to help support players that wanted to construct dragon-themed decks. Dragon cards in Hearthstone are generally expensive to cast and thus only appear in the latter part of a match, making such decks weaker in the opening rounds. With "Blackrock Mountain", the team introduced cards that interacted with dragon cards, such as by having special effects when a minion is summoned while having a dragon card in hand.

The Grand Tournament

The expansion "The Grand Tournament" was announced on July 22, 2015, and was released on August 24; the set includes 132 cards found in its specific card pack, which costs the same as previous card packs. "The Grand Tournament" was developed with a new card mechanic for minions called "Joust" which has combat between a minion with Joust with other minions based on the casting cost of the minions, rather than their attack and health. Donais noted that while this also created a central theme for "The Grand Tournament" expansion, it also served to help combat "aggro" decks—decks filled with low-cost minions that could be quickly deployed—which at the time of the expansion's release, were extremely popular and found to be discouraging to many players. "The Grand Tournament" also introduced the "Inspire" mechanic for minions, which would create some effect for the minion each time the player used their Hero power, often including cumulative effects over several turns. Donais said the Inspire keyword came about looking at how to interact with Hero powers better, and while Inspire-based cards could be slow and at risk, could have great payoffs if used properly

League of Explorers

The adventure "League of Explorers" was announced at BlizzCon 2015 on November 6, 2015, and the first wing was released on November 12; the other three wings were opened weekly with a week-long break after the second wing. It includes 13 bosses and nine class challenges that together awards 45 cards, which includes five legendaries, and an exclusive card back if all heroic bosses are defeated.[48] "League of Explorers" was the team's first attempt to craft a narrative that allowed Hearthstone to stand on its own from the Warcraft universe even though it may still borrow concepts from it from time to time. The adventure borrows from dungeons in desert locations within World of Warcraft but transform the experience to be one of an adventuring archaeologist, and the challenges were more themed around puzzles and traps that the dungeons would present rather than just boss characters. Central to "League of Explores" was the new "Discover" mechanic, which when activated would have the game randomly select up to three cards with specific characteristics from all available game cards, allowing them to select one card to put into their hand. This mechanic was introduced to provide contrast to decks that focused on card draws, which they found out tend to be played in the same manner over time. The Discover mechanic allowed decks to be more random but provide some player decision for on-the-spot judgement calls depending on the situation.

Whispers of the Old Gods

The expansion "Whispers of the Old Gods" was announced on March 11, 2016, and was released on April 26; the set includes 134 cards found in its specific card pack, which costs the same as previous card packs.[50][51]"Whispers of the Old Gods" was based on creating a theme around mysterious and dark Lovecraftian horror, such as Cthulhu, to contrast to the high adventure and excitement that they had designed with "League of Explorers". This concept of crafting powerful god-like characters let them brainstorm on wild ideas for cards that may seem overpowered for the game but that would fit the theme. Central to the expansion is the Legendary "C'Thun" Old God card, which can be buffed by effects from sixteen other cards, disciples of C'Thun, that were part of the expansion, regardless of where the C'Thun card was currently at. Donais explained this helped to create a "sense of dread" in opponents that fit the theme they wanted. Because of this, all players received the C'Thun card and one of the disciple cards for free once this expansion was released. "Whispers" also allowed the designers to take old favorite cards and make "corrupted" versions of them within the flavor of the theme.

One Night in Karazhan

The adventure "One Night in Karazhan" was announced on July 29, 2016, and the first wing was released on August 11; the other three wings were opened weekly thereafter. There are four wings along with a free prologue mission that awards two cards. Kara includes 13 bosses and nine class challenges that together awards 45 cards, which includes five legendaries, and an exclusive card back if all heroic bosses are defeated. "One Night in Karazhan" is based on a popular game location in World of Warcraft, featuring an abandoned mage's tower that is often used for a dungeon raid. The adventure features eleven boss characters that are also in the World of Warcraft raid of the tower. The team had designed the concept of this expansion alongside "Curse of Naxxramas" early in Hearthstone's post-release and was considered to be their first adventure, but they ultimately used Naxxramas, as Karazhan was being used for other activities by teams within Blizzard at that time. Instead, when they looked towards designing it, they found Priest decks had difficulty in staying current with the meta-game, so several of the cards introduced with this set were to help make the Priest a more viable class with the shifts in popular decks.

Mean Streets of Gadgetzan

The expansion "Mean Streets of Gadgetzan" was announced at BlizzCon 2016 on November 4, 2016, and was released on December 1; the set includes 132 cards found in its specific card pack. "Mean Streets of Gadgetzan" was originally envisioned to have the spirit of "cops and robbers", according to designer Matt Place and art director Ben Thompson, but the idea transformed into squarely focusing on the crime aspects, and treating the narrative as three principle mafia-like crime families vying for control of the city of Gadgetzan along with a number of small-time criminals that work as hired hands. The nine hero archtypes were divided into sets of three that each worked for a different family, which led to the creation of tri-class specific cards. Each of the three families were given a central mechanic theme: the Grimy Goons buff cards that in a player's hand, the Jade Lotus improve new Jade Golem cards the more they are played, and the Kabal use Discover cards to use certain cards from outside a player's deck. The set includes Legendary cards that represent the leader of each family.

Journey to Un'Goro

The expansion "Journey to Un'Goro" was announced on February 27, 2017, and was released on April 6; it contains 135 cards found in its specific card pack. "Journey to Un'Goro" is based around a pre-historic theme and introduces dinosaurs and the Elemental tribe, including retroactively making some previously released minions as part of the tribe. It introduces Legendary spells with the "Quest" keyword, which award a unique minion or spell when the conditions of the quest are fulfilled. If a Quest card is in the player's deck it will be put into the player's opening hand, although players are allowed to mulligan it, and it must be put into play before the player can start completion of that quest. The expansion also adds the "Adapt" keyword to some minions and spells, which allows the player to select a buff to apply to one or more minions

Knights of the Frozen Throne

The expansion "Knights of the Frozen Throne" was announced on July 6, 2017 and was released on August 10. The set's theme is about the frozen wastes of Northrend and Icecrown Citadel, and the set features the game's heroes embracing the power of the Undead Scourge, becoming Death Knights in the service of the Lich King. The expansion features the introduction of hero cards, an entirely new card type which transforms the player's hero and hero power along with varying unique effects, and the Lifesteal mechanic. It features 135 cards and includes adventure-like missions for single-players, featuring a narrative leading to a boss fight with the Lich King that can reward one random Legendary death knight card, multiple card packs and for dedicated players an alternate hero for Paladin - Arthas. The expansion introduced the Lifesteal keyword; when minions or spells with this keyword deal damage the controlling hero is healed by the same amount.

Kobolds & Catacombs

The expansion "Kobolds & Catacombs" was announced in November 2017 during BlizzCon 2017 and was released on December 7, 2017. The general concept of the expansion was around the idea of dungeon crawls from role-playing games. Its 135 cards are themed around exploring old catacombs under Azeroth and uncovering valuable treasures. Among the cards include Legendary weapons for each class that includes classes that have never had weapons before, Spellstone cards that require the player to achieve certain objectives in-game to upgrade the card, "Unidentified" item cards that offer a random effect alongside a known effect, and cards with a "Recruit" keyword that allow the player to summon minions directly from their deck that meet the card's requirements. All players received the Legendary minion Marin the Fox a month ahead of time and after the set was released, one random Legendary weapon card. Earlier in 2017, Blizzard had planned for this set's theme to be around Warcraft's Blingtron robots and would have been known as "Blingtron's Lootapolooza". While this theme still centered around dungeons and loot, they decided that the set would have better flavor and easier art to design by switching the theme to kobolds; however, this decision came after they started some of the promotional material, so some of the art includes Blingtrons.The expansion introduces a new single-player mode called a "Dungeon Run", a roguelike-style format. The goal for the player is to complete battles against eight boss characters randomly selected from a pool of 48 that become more progressively difficult. The player starts by selecting a class, which gains them a small deck of cards for that class. For each boss they defeat, the player gains additional starting health in the next battle, a choice of three sets of three randomly selected cards around a theme, and in some cases, a unique treasure card otherwise not available in the normal game modes. Should the player be defeated by a boss, that run is ended, and the player must start a run anew. Cards from the Dungeon Run do not become part of the player's library, though players can earn card packs through quests involving Dungeon Runs, and can earn a unique card back by completing runs with all nine classes.[61] The idea for the Dungeon Run is based on the expansion's theme and the mode works as an optional single-player experience independent of the card collection of the player.

The Witchwood

The Witchwood was announced in March 2018 as the first expansion in the Year of the Raven and was released on April 12, 2018. It is themed around a spooky forest next to the cursed city of Gilneas from Warcraft. The expansion adds two new keywords; "Echo" cards can be played as many times on a turn as long as the player has the mana to pay the cost, while minions with "Rush" can immediately attack the opponent's minions on the turn they are summoned. The set also features cards that give a special effect if a player's deck only contains even-cost cards or odd-cost cards, effectively limiting players to only half of their card collection in assembling decks to take advantage of these cards. The expansion adds a single-player mode called "Monster Hunt" that is an evolved version of Kobolds & Catacombs's "Dungeon Run" that became available to play two weeks after the expansion was released. In the "Monster Hunt", players pick between four unique heroes that have a unique hero power and unique cards. After defeating each encounter, players pick between three sets of cards to improve their deck and occasionally earn special cards or an ability to improve their hero power; there are over 45 encounters. Players can earn a unique card back, which requires defeating eight bosses of increasing difficulty, with each of the four heroes and then defeating the final boss Hagatha the Witch

The Boomsday Project

The Boomsday Project was announced in July 2018 with a planned release on August 7, 2018. The set focuses on mech characters and abilities, similar to Goblins & Gnomes, themed around the minion Dr. Boom that was introduced in the former set, having set up a villainous laboratory in the Netherstorm. Among new gameplay additions include the "Magnetic" keyword, which allows cards with it to become combined, and a new legendary spell card for each class. The set will also include a single player mode called the Puzzle Lab that is missions with different objectives, such as Lethal, where players must win the match during their turn, and Mirror requires player to match the minion battlefield on both sides