21 is a tense survival card game based on the rules of blackjack. Two players are trapped at a table and forced to play against each other. The winner survives, while the loser receives a deadly punishment.
Players take turns drawing cards, trying to reach a total as close to 21 as possible without going over. When both players end their turn, the hidden cards are revealed and the winner of the round is determined.
The player who loses receives a punishment depending on the game mode.
The game continues until one of the players dies.