Alternation is a solitaire card game which is played using two decks of playing cards.
Forty-nine cards are set up into seven columns of seven cards each. In each column, the top card, the third and fifth cards from the top and the bottom card are face up. The second, fourth, and sixth cards from the top are face down. This results in an alternating OXOXOXO pattern.
The object of the game is to release the Aces as they become available, creating foundations, and to then build up each suit from the Ace.
The top cards of each column are available for play, to be built up by suit on the foundations, or on each other down by alternating colors. A sequence or part of a sequence can be moved as a unit.
When no more cards can be moved, the stock (the remaining cards) is dealt one card at a time. A card that cannot be built on the tableau or on the foundations is placed on the waste pile, the top card of which is available for play.
The game is won when all cards are built onto the foundations. If this is not achieved, the game ends after the entire stock has run out. There is no redeal.