Solitaire Double: Klondike with two packs, and nearly twice the wins
Solitaire Double is Klondike played with two full packs shuffled together: 104 cards, nine columns and eight foundations. It feels roomier than the one-pack game, and our tests suggest it is far kinder. A simple computer player that won 42.3% of ordinary Klondike deals won 81.5% of two-pack deals over 10,000 games. This page explains the rules as this site plays them, what our numbers show, and why a second pack makes such a difference.
One honest note up front: the peer-reviewed study we compare our work with on this site, from the University of St Andrews, does not cover the two-pack game. So every figure here is our own, and there is no published number to set it against.
The two-pack game in figures
| Measure | Two packs (Solitaire Double) | One pack (Klondike Turn 1) | Deals |
|---|---|---|---|
| Computer player's win rate | 81.5% (95% range 80.7–82.2%) | 42.3% (41.3–43.3%) | 10,000 each |
| Deals with no opening move in the tableau | 2.7% | 8.6% | 10,000 each |
| Aces that start face down | 2.8 of 8 | 1.6 of 4 | 10,000 each |
| Moves in a won game | about 268 | – | 8,145 wins |
| Passes through the stock in a won game | 2.7 | 2.3 | won games |
| Published figure (St Andrews study) | None: the two-pack game is not in the study | – | |
The computer player sees only the face-up cards and never takes a move back, so its win rate is a floor: a careful person using Undo can expect to do better.
The rules on this site
Setting out
Two standard packs are shuffled together. Nine columns are dealt, holding one to nine cards from left to right, with only the top card of each face up. That uses 45 cards; the other 59 form the stock.
Building
- In the columns, build down in alternating colours: a red 8 on a black 9.
- Face-up runs can be moved together.
- Only a King, or a run starting with a King, can go into an empty column.
The eight foundations
There are two foundations for every suit, each built from Ace to King. That means two Aces of hearts, for instance, can both start piles.
The stock
Cards turn one at a time from the stock to the waste, and you may go through the stock as often as you like. (The page's three-card option takes you to our one-pack Solitaire Turn 3; the two-pack game is played one card at a time.)
Winning
Get all 104 cards onto the eight foundations. It is a long game: our player's wins averaged about 268 moves, including turns of the stock.
Why a second pack helps so much
Two homes for every card
With two foundations per suit, a card has twice as many places to go. A 5 of clubs is not stuck waiting for one particular 4 of clubs; either of the two will do.
More landing spots in the columns
Every card has two possible partners of the right rank and colour in each pack, so four in total across two packs. With nine columns and plenty of cards in play, you are rarely short of somewhere to put a card.
A dead start is rare
In ordinary Klondike, 8.6% of our deals offered no move at all among the seven face-up cards. With nine columns and two packs, that fell to 2.7%.
But more cards are hidden
The nine columns hide 36 cards face down, and on average 2.8 of the eight Aces start buried. So the digging still matters — there is simply more room to dig with.
Tips drawn from the numbers
Plan for a long game
At around 268 moves for a typical win, this is not a five-minute game. Settle in, and don't rush the early moves.
Don't fear the stock
Won games went through the stock 2.7 times on average. Going round again is normal.
Start the second foundation of a suit early
When a second Ace of a suit appears, put it up. Two piles per suit mean twice the chance of placing the next card.
Uncover the right-hand columns
The ninth column holds eight face-down cards. Getting at those opens up the game more than anything else.
Keep an empty column for a useful King
Only Kings may go in, so don't clear a column until one is ready to move.
Playing Solitaire Double here
The game runs in any modern browser on a computer, tablet or phone. It is free, with nothing to install and no sign-up. The cards are large and clear, with a zoom control; Hint, unlimited Undo, Restart and Auto Play are all available; and you can drag cards or tap to move them. Wins, time and moves are tracked for the current game, sound can be switched off, and there is a fullscreen mode and a choice of table colours.
How we ran the research, step by step
- Reading the rules. We read the two-pack game's code on this site: nine columns of one to nine cards, a 59-card stock, one card per turn, unlimited redeals, Kings only into empty columns, two foundations per suit.
- Building the program. We extended our one-pack Klondike program to two packs, nine columns and eight foundations.
- Dealing. 10,000 deals (seeds 1 to 10,000), each shuffled from a numbered seed so it can be dealt again.
- The player. A rule-based computer player that sees only face-up cards and never undoes a move, the same approach as for one-pack Klondike, so the two results can be compared fairly.
- Looking at the deals. Before play, we counted buried Aces and whether any move was possible at the start.
- Checking against published research. We searched the St Andrews study (Blake and Gent, Journal of Artificial Intelligence Research, 2026) and found no two-pack Klondike figure, so there is nothing to compare with.
- Margin of error. The 95% range of 80.7% to 82.2% is where the true win rate of this player very probably lies.
- Limits. This is a floor, not a measure of how many deals can be won. We did not run a solver that sees every card for this game.
Behind the numbers: the code
The program is written in Python 3.11 with only the standard library, in a module called doubleklondike.py that generalises our one-pack Klondike player to two packs. A shared runner spread the 10,000 deals across the cores of one machine using Python's multiprocessing; the whole run took only a few seconds. Win rates carry a Wilson score interval. We used Claude, the AI assistant from Anthropic, to help write and review this code and to draft the page. The AI did not supply any figures: each one comes from running the program.
Frequently asked questions
Is Solitaire Double easier than normal Solitaire?
By our measure, yes: the same simple player won 81.5% of two-pack deals against 42.3% of one-pack deals.
Can I play it three cards at a time?
Not on this site. The three-card option leads to the one-pack Solitaire Turn 3.
Why are there two foundations for each suit?
Because there are two of every card. Each foundation still runs Ace to King in one suit.
Has anyone published how winnable the two-pack game is?
Not in the St Andrews study, and we have not found another reliable figure. Ours is a floor from a simple player.
What else uses two packs?
Try FreeCell Two Decks, Forty Thieves or Diplomat, or the single-pack Klondike Solitaire.
By Admin, solitaire-free.uk. Study date: 19 September 2026.