casino war is based on a children card game. If the player's card is higher then the house, he wins the amount equal to his bet, if the house card is higher, the player loses.

House advantage: The house and the player each have a 50% chance of winning, so this seems like an even money game. The dealer advantage, however, comes from what happens in the case the player and the house has the same card. Some casinos offer a bonus payout in the event of a tie after going to war. The house advantage for this game is usually over 2%. The house advantage increases with the number of decks in play and decreases in casinos who offer a bonus payout. 
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