A deck-building game is a card game that uses building a deck as the main focus of the gameplay. It is 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. Typically, the cards provide a type of game currency which allows a player to buy more cards to add to their deck.
The original deck-building game was Dominion, whose popularity spurred the creation of many others: notably Thunderstone, Ascension: Chronicle of the Godslayer, and Legendary (based on Marvel superhero comics). Other games, such as the Mage Knight board game, Warring Kingdom, A Few Acres of Snow and Copycat, use deck-building as one mechanic among many, instead of the main focus of the game.