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 players to buy more cards to add to their decks.
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). Some games, such as the Mage Knight board game, include deck-building, but not as the primary focus of gameplay.