Klondike is a solitaire card game often known purely by the name of Solitaire. It is probably the most well-known solo card game.

Taking a standard 52-card deck of playing cards (without Jokers), deal one upturned card on the left of your playing area, then six downturned cards (from left to right). On top of the downturned cards, deal an upturned card on the left-most downturned pile, and downturned cards on the rest until all piles have an upturned card. The pile should look like the following figure:

              O   O   O   O
 
 
 +-+ +-+ +-+ +-+ +-+ +-+ +-+
 | | +-+ +-+ +-+ +-+ +-+ +-+
 +-+ | | +-+ +-+ +-+ +-+ +-+
     +-+ | | +-+ +-+ +-+ +-+
         +-+ | | +-+ +-+ +-+
             +-+ | | +-+ +-+
                 +-+ | | +-+
                     +-+ | |
                         +-+                           

The four foundations (represented by O in the figure) are built up by suit from Ace to King, and the tableau piles can be built down by alternate colours, and partial or complete piles can be moved if they are built down by alternate colours also. Any empty piles can be filled with a King or a pile of cards with a King at the top.

There are different ways of dealing the remainder of the deck:

Turning three cards at once to the waste, either allowing three passes through the deck or placing no limit on passes through the deck. 
Turning three cards at once, reversing the order of each group of three as the cards are dealt. 
Turning only one card at a time, but only passing through the deck once. 

Microsoft has included Klondike as part of the Windows operating system since the 3.x series, starting from 1990. The game was developed by the (now-former) Microsoft programmer Wes Cherry, who famously received no revenue from his endeavours; and the card deck itself was designed by Macintosh pioneer Susan Kare. GNOME and KDE have also provided corresponding applications (sol and kpat) since early versions.

It has been reported to be the most commonly played computer game in recent history, possibly ranking higher than even Tetris.

Odds of winning
At the moment, no one knows what proportion of Klondike games can be won. No one has managed to find a mathematical model for the game that is simple enough to allow direct computation of this probability.

A modified version of the game called "Thoughtful Solitaire" has a known solution strategy that works 70% of the time but requires significant computing power. This solution strategy does not solve every deck that is solvable, but is about twice as good as the best human players. The difference between Klondike and "Thoughtful Solitaire" is that in "Thoughtful Solitaire" the player can see the identity of all the cards on the table at the beginning of the game.


Strategies for winning
As you go through the deck, try to memorize all the cards you have seen, and where they occurred in the deck.