Six full decks, 312 cards, 23 tableau columns, and 24 foundations: Sextuple Klondike blows classic Klondike up to a genuinely epic scale.

Sextuple Klondike Solitaire is Klondike blown up to a genuinely enormous scale: six full decks, 312 cards, twenty-three tableau columns, and twenty-four foundations to fill. It is one of the largest patiences you can play, and a single deal can happily fill a long session. The tableau is dealt in the usual triangular fashion, with only the top card of each column face-up.
The rules are pure Klondike. You build the tableau down in alternating colours, send cards up to the foundations in suit from Ace to King, and turn the stock three cards at a time. With six of every card in circulation there is almost always a legal move somewhere on the board, and because you may recycle the stock as many times as you like, very few deals ever grind to a true dead end.
Scale rewards patience over speed. Only a King, or a run led by a King, may occupy an empty column, so guard those spaces before you fill one. Try to keep the foundations climbing evenly across the suits rather than racing a single pile up to the King, and dig out the face-down cards steadily so the board keeps opening up.
If six decks feels like one too many, Quintuple Klondike Solitaire gives you nearly the same scale with one less deck in play, and Double Klondike Solitaire is the gentler entry point into multi-deck Klondike.
If you'd rather start smaller, the original Solitaire is the classic this whole family builds on.
If you run into anything odd or have an idea that would make the game better, please contact me.
Enjoy!
24 foundation piles: Build up from Ace to King in the same suit.
23 tableau piles: Alternate colour construction, building down. Move groups of cards down by alternating colour when they are in sequence. Fill empty columns with a King or a legal run of cards led by a King. At the start of the game one card is dealt to the first pile, two cards to the second, and so on. The top card of each pile is shown.
Stock: Click to deal three cards at a time to the waste. Redeals are unlimited.
Waste: The top card is always available for play on the foundations or the tableau.
There are twenty-four foundation piles.
Any Ace may be moved to an empty foundation pile to start it.
A card can be added to a foundation pile only if it's one rank higher and the same suit as the pile's current top card, so the only card that fits on a Q of spades is a K of spades. There can be no more than 13 cards in a pile.
The top card of each foundation can be moved back into play if another pile will accept it.
There are twenty-three tableau piles, with one card in the first pile, two cards in the second, three in the third, and so on. The top card in each pile is dealt face-up, while the remaining cards are dealt face-down.
A card can be added to a tableau pile only if it's one rank lower and the opposite colour of the pile's current top card, so the only cards that fit on the 6 of clubs are the 5 of hearts and 5 of diamonds.
Cards on the tableau that are not covered by another card are free to be played onto the foundation or any other tableau pile.
Only Kings may fill empty spots in the tableau. If the cards run alternately red and black, groups of cards in sequence from high to low may be shifted from one column to another.
There is one waste pile, and the remaining cards form the stock.
When you click on the stock, three cards are dealt to the waste. The stock may be recycled an unlimited number of times; once it is empty, the waste is turned back over to form a new stock. The top card of the waste can be played to the tableau or foundation.