Forty Thieves Solitaire: the two-pack test of patience

Forty Thieves is a demanding two-pack game, and our study shows why. Ten columns of four face-up cards, a 64-card stock you get to go through only once, same-suit building, and just one card moving at a time. There is very little room for error, and a winning game is long.

How long? Our computer player's wins took about 277 moves each. And wins were rare for it: across 3,000 deals it got home in only 5.8%, typically clearing about a third of the 104 cards before running out of options.

What our computer player found

A word of caution: the 5.8% is a floor, and a low one. Our player does not know what is coming in the stock, never undoes a move, and plans only a short way ahead. A patient human using Undo will do clearly better. The figure shows how unforgiving the game is to casual play, not how winnable it truly is.

Forty Thieves on solitaire-online.nz

Ten short columns and a big stock

• Two packs, 104 cards in all.
• Ten columns of four cards, all face up: 40 cards on the table.
• A stock of the other 64 cards.
• Eight foundations, two per suit, built up from Ace to King.

One card, one suit, one pass

• Build down in the columns in the same suit: the 9♣ goes on the 10♣.
• Only one card moves at a time. There are no run moves.
• Any card can go into an empty column.
• The stock turns one card at a time to the waste, whose top card is playable.
• There is no redeal. When the stock runs out, it is gone.

Why the games are so long

Everything about Forty Thieves stretches a game out. There are 104 cards to get home. The stock alone is 64 taps. And because cards move one at a time, shifting a run of five cards to another column takes five moves, plus spare space to do it.

Put together, that is why our player's wins averaged about 277 moves, more than twice a typical single-pack Klondike win. Forty Thieves is a game for a long, quiet session, not a quick break.

Strategies for a long session

Empty a column before anything else

With one-card moves, an empty column is your only working space. Any card can go into it, so use it to shuffle cards between columns and untangle same-suit runs.

Lift the visible Aces first

In 57% of our deals at least one Ace was already playable from the opening layout. Get those up, then look for 2s.

Watch the stock closely

You go through the stock once. A card you skip is buried in the waste, and you can only reach it again by playing every card on top of it. Before turning the next card, make sure the current one has no useful home.

Do not over-build long runs

Long same-suit runs look like progress, but with single-card moves they are slow to relocate. Build them where they can stay, ideally on a foundation-bound path.

Test lines with Undo

With no second pass through the stock, one early misstep can cost the game. Undo is unlimited here; use it to test a line before you commit.

Forty Thieves on a phone or tablet

Ten columns and eight foundations make this a wide layout. On a phone, turn it sideways, zoom in, and tap rather than drag. On a tablet or computer it is more relaxed. The game shows the moves and time for the current deal, which helps if you want to see how a long game went.

How far a typical game gets

Because our player won so rarely, the more telling figure is how far it got overall. Across all 3,000 deals it averaged about 34 of the 104 cards on the foundations by the end. That hints at what a Forty Thieves session often looks like: a steady start as the visible Aces and low cards go up, then a point where the stock runs out and the columns lock.

Compare that with Diplomat, another two-pack game with a single pass through the stock. The same kind of player, built for Diplomat first and then adapted for Forty Thieves, won 47.9% of Diplomat deals and averaged 76 of 104 cards home. One clear difference in the rules is building: Diplomat lets you build in any suit, while Forty Thieves insists on the same suit.

So if Forty Thieves feels too tight, Diplomat gives you a similar long two-pack game with more room to manoeuvre. And if you want two packs with plenty of wins, Solitaire Double is the most forgiving of the three.

How we did the research, step by step

In September 2026 the solitaire-online.nz team added Forty Thieves to its study, to see how long a winning game takes and how far an ordinary, no-peeking player gets.

1. Rules from the site code. Two packs, ten columns of four face-up cards, a 64-card stock turned one at a time with no redeal, same-suit building, one card at a time, and any card to an empty column.
2. A copy of the game. We wrote these rules into a program, reusing the player we built for Diplomat with the rules changed.
3. Numbered deals. 3,000 deals from seeds 1 to 3,000.
4. A no-peeking player. It sees only what you see, does not know the order of the stock, and never undoes a move. That makes its win rate a floor.
5. Short look-ahead. On each turn it tries up to 300 positions ahead from the table and waste, and turns the next stock card only when nothing improves its position.
6. Published results. We found no published figure for Forty Thieves, so there is nothing to compare against.
7. Error bars. The 5.8% has a 95% range of 5.0% to 6.7%.
8. Limits. We did not build a solver that sees every card for this game, so we cannot say what share of deals is winnable with perfect play. Treat 5.8% as a floor only.

The technical side

The code is fortythieves.py, written in Python 3.11 using only the standard library. The player scores each position (50 points for each card on a foundation, a penalty for cards covering lower ones, a small bonus for same-suit links and for empty columns) and uses a best-first look-ahead of up to 300 positions per turn, keeping a record of positions already seen. runner.py spread the deals across processor cores with Python's multiprocessing; all 3,000 took about half a minute. The 95% ranges are Wilson score intervals. An AI assistant, Claude by Anthropic, helped write and review the code and draft this page. Every number comes from running the code.

By Admin, solitaire-online.nz. Study date: 19 September 2026.

Short answers before your next deal

How long is a game of Forty Thieves?

Long. Our player's wins took about 277 moves each, including taps on the stock.

Is there any redeal?

No. There is no redeal in Forty Thieves on this site.

Why do so many Forty Thieves games end early?

For a player without look-ahead or Undo, yes: ours won 5.8%. A patient player with Undo does clearly better.

Do runs move together here?

No. Cards move one at a time, which is a big part of the challenge.

Which two-pack game is easier going?

Solitaire Double is much kinder, and Diplomat sits in between. Or browse the games page.