A standard deck of cards (with or without Jokers)
Each player starts with half of the shuffled deck. Players may not look at the cards in their hands. Each player pulls one card from the deck and puts it on the table. The higher card wins; the player who played it takes both cards and places them on the bottom of his stack. Aces are always higher than Kings in this game, but they are often lower than Jokers (if used).
A “war” occurs when the two players play the same rank (two 9s, for example), making a tie. Each player then deals three cards facedown (the spoils are for the winner) and a face-up card. The player with the higher face-up card takes all the cards from the war into his stack.
The player who accumulates all the cards wins the game.
Have more than two players?
You can play with more than two players, by instituting a variation on the rules. The only time there is a war is when the two highest cards tie. These two players only battle in the traditional fashion, and the winner keeps all cards from the hand.