Blackjack is a casino banking game. It is the most widely played casino banking game in the world. This family of card games also includes. Blackjack · [HOST] · Doom 3 · Doom 2: Hell on Earth · DOOM · Head Soccer · Bloxorz Zap and Destroy · Zombie Pacman · Zombies Can't Jump · Zombies Can't Jump. . It uses decks of 52 cards and descends from a global family of casino banking games known as "twenty-one".