Solitaire Double: Klondike with a second deck, and a win rate that nearly doubles
Take ordinary Klondike, shuffle in a second deck, add two columns and four foundations, and you have Solitaire Double. Of every pair of games on this site, this one shows the effect of doubling the deck most sharply, because we played both versions with the same simple program.
That program sees only face-up cards, follows a fixed list of move priorities and never undoes. On one deck it won 42.3% of 10,000 deals. On two decks it won 81.5% of 10,000 (95% range 80.7%–82.2%). Same logic, same one-card draw, same unlimited redeals: the extra deck alone moved the result by about 39 points. The price is length: its two-deck wins took about 268 moves, roughly twice as many.
At a glance: one deck vs two, same program
| Measure | Klondike, 1 deck | Solitaire Double, 2 decks |
|---|---|---|
| Program win rate (floor) | 42.3% (41.3–43.3%), 10,000 deals | 81.5% (80.7–82.2%), 10,000 deals |
| Moves in won games, draws included | 126.2 (125.9–126.4), 4,229 wins | 268.1 (267.8–268.4), 8,145 wins |
| Stock passes in won games | 2.34 (2.32–2.36) | 2.69 (2.67–2.70) |
| No move among the face-up cards at the start | 8.6% (8.1–9.2%) | 2.7% (2.4–3.0%) |
| Aces starting face down | 1.60 of 4 (1.59–1.62) | 2.79 of 8 (2.76–2.81) |
| Planning search (winnable in principle) | 76.6% proven (73.9–79.1%), 1,000 deals | not run |
The last row is the honest gap: we have no ceiling for the two-deck game, and Blake and Gent (2026) do not cover it either. The 81.5% is a floor for a person, not an estimate of how many deals can be won.
Why the second deck helps so much
Twice the landing spots
Every card has a twin. A red 6 can go on any of four black 7s instead of two, and each suit has two foundation piles. The simple program rarely gets stuck because there is usually a second copy of the card it needs somewhere in reach.
Fewer dead openings
Only 2.7% of two-deck layouts start with no move at all among the nine face-up cards, against 8.6% of one-deck layouts.
More hidden cards, but less damage
About 2.8 of the 8 Aces start face down, a larger count than one deck's 1.6 of 4 but a smaller share. A missing Ace hurts less when its twin may be in plain view.
The rules here
- Cards: two standard decks, 104 cards.
- Tableau: nine columns of one to nine cards, top card face up.
- Stock: the remaining 59 cards, one at a time, unlimited redeals. The Draw 3 option leads to one-deck Solitaire Turn 3.
- Foundations: eight, two per suit, Ace to King.
- Building: down in alternating colors; ordered runs move as a unit.
- Empty columns: Kings, or runs headed by a King.
Playing the long two-deck game well
Pick the twin that digs
When two cards could take your move, choose the one sitting on more face-down cards. Freeing it later opens more of the table.
Start on the tall columns
The right-hand columns hold most of the hidden cards. Work toward them early.
Keep the twin foundations level
Two piles per suit tempt you to rush one. Build them evenly so mid-rank cards stay available as landing spots.
Budget your attention
A two-deck win runs past 250 moves. Mistakes late in the game are the ones that cost, so slow down when the table thins out.
Solitaire Double on freecell-two-decks.com
Free in any modern browser on computer, tablet or phone, no sign-up. Zoom and fullscreen keep nine columns readable. Hint, unlimited Undo, Restart, Auto Play, drag or tap to move, and a counter for wins, time and moves are included, with sound and table color in the settings.
How we measured it
The freecell-two-decks.com team ran this test on September 19, 2026, on the rules in this site's own game code.
- Rules from the code: 104 cards, nine columns, 59-card stock, one-card draw, unlimited redeals, Kings-only spaces.
- Extended our Python Klondike program to nine columns and paired foundations, keeping the same move priorities as the one-deck program.
- 10,000 numbered deals, seeds 1–10,000.
- One player: the priority-list program, face-up cards only, no Undo.
- Opening layouts inspected for Aces face down and dead starts.
- No planning search and no published figure, so there is no ceiling for this game.
- Ranges: Wilson score for percentages, normal intervals for averages.
Python 3.11, standard library only. Claude, an AI assistant by Anthropic, helped build and check the program and draft this page; every figure comes from running the code.
Solitaire Double questions
Does a second deck make Klondike easier?
For our simple program, much easier: 81.5% won against 42.3% on one deck.
Then why is FreeCell Two Decks not easier than FreeCell?
Because in FreeCell nothing is hidden, so twins add length more than rescue. See FreeCell Two Decks for the figures.
Can I play three-card draw with two decks?
No. Draw 3 goes to one-deck Solitaire Turn 3.
What next?
Try the site's main game, FreeCell Two Decks, or another 104-card game such as Forty Thieves. All games are on the games page.
By Admin, freecell-two-decks.com (Forty Media). Research run September 2026.