A deck-building game is a card game or board game where construction of a deck of cards is a main element of gameplay.^[1] Deck-building games are similar to collectible card games (CCGs) in that each player has their own deck. However, unlike CCGs, the cards are not sold in randomized packs, and the majority of the deck is built during the game, instead of before the game.

In most deck-building games, each player starts with a small deck of cards of low value. Each turn, they draw some cards from their deck and play them, which may have various gameplay effects, and may buy more cards from a central market, thereby building their deck. The effects of playing cards often include providing the in-game currency that allows players to buy cards; other effects may include increasing the number of game actions a player may take on their turn, removing unwanted cards from the player’s deck, or attacking other players. As players buy more cards with more valuable abilities, their decks gradually become more powerful. When the player runs out of cards to draw, they shuffle their discard pile (which usually includes newly-gained cards) to create a new deck to draw from. Apart from this, however, games may vary; for instance, some are competitive, while others are co-operative.^[2]

As players do not build their decks before playing, they cannot organize a deck in advance, and must do so during play. Therefore, strategy is driven by the cards available in the market, which may vary from game to game.^[3] In some games (such as Legendary: A Marvel Deck Building Game), before the game begins, players can strategize and choose which cards go into the central market deck (the cards that can potentially be bought to increase the strength of each player’s deck).^[4]

Deck-building is the central mechanic in some games, such as Dominion or Star Realms. However, in others, such as the Mage Knight Board Game or Arkham Horror: The Card Game, it is combined with others.^[2]

If a game has similar mechanics, but doesn't use cards, it is frequently called a pool-building game.

While StarCraft: The Board Game (published in 2007) was the first deck-building game,^{[citation needed]} Dominion was the first popular deck-building game that set the standard for the genre.^[5][6] Its popularity spurred the creation of many others, including Thunderstone, Ascension: Chronicle of the Godslayer,^[7] Legendary (based on Marvel superhero comics) published by Upper Deck, and Clank! published by Renegade. In many cases, computerized versions of deck-building games are available, usually mimicking the tabletop version. For example, Dominion^[8] and Star Realms^[9] can be played online.

Deck-building elements can be used as part of larger video games, such as Kingdom Hearts: Chain of Memories and Metal Gear Acid which integrate deck-based combat systems into established game series.

A novel version of the tabletop version of deck-building games are roguelike deck-building video games. Typically single-player games, these games combine deck-building with procedurally generated scenarios and rewards, a fundamental principle of roguelike games. These games require the player to build their deck as they play, usually having to add cards from a random selection as a reward for completing objectives. While the first known example of such a game was Dream Quest, the genre gained momentum with the release of Slay the Spire in 2017.^[17]

• Dedicated deck card game