Play Interchange Solitaire — Every Other Card Is Hidden

Interchange takes the Forty Thieves family somewhere none of its relatives go. Seven columns are dealt seven deep, and the rows alternate: the first face up, the second face down, the third face up, and so on to the bottom of the board. Every column therefore holds four cards you can see and three you cannot, interleaved — so digging is never a straight run of known cards, it is a known card, then a surprise, then a known card. Add suit building, moving runs and spaces that only a King may enter, and you have the hardest open-stock game in this family. Free in your browser, no sign-up.

How Do You Play Interchange?

Goal: build all eight foundations from Ace to King by suit.

Setup

• Decks: two standard decks, 104 cards.
• Tableau: seven columns of seven (49 cards). Rows alternate face up and face down, starting face up — so each column shows four cards and hides three, twenty-one hidden in all.
• Foundations: eight, empty. Every Ace starts buried or in the stock.
• Stock: the remaining 55 cards, turned one at a time to a waste. No redeal.

Rules

• Build tableau columns down by suit: the 7 of spades onto the 8 of spades, and nothing else.
• A packed same-suit run moves as a unit. Without this the seven-deep columns would be undiggable.
• Only a King, or a King-headed run, may enter an empty column. No other card can take a space.
• A face-down card turns up the moment play exposes it, and is then an ordinary playable card.
• Foundations build up by suit from the Ace and are one-way.
• One pass through the stock, one card at a time. There is no redeal.

Interchange Strategy

This is a hard game and it deserves to be played carefully. The alternating rows mean that the cost of every dig is known only halfway.

• Count the hidden cards under each target, not the visible ones. A column showing an attractive card may hide three unknowns beneath it. Because the rows alternate, the pattern is always the same: peel a visible card and you meet a hidden one; peel that and you meet another visible one. Plan two layers at a time.
• Turn hidden cards even when the move looks pointless. Information is the scarce resource here, not tempo. A move that exposes a face-down card is usually worth more than a tidy build that exposes nothing, because you cannot plan around twenty-one cards you have never seen.
• Treat a space as a King's parking bay, not as storage. Only Kings enter, so an empty column is worth exactly as much as your ability to put a King in it and build downward from there. If no King is available or reachable, clearing a column buys you very little.
• Move runs, and build them deliberately. The unit move is what makes this game playable at all. Assembling a long same-suit run in one column and then relocating the whole thing is often the only way to reach what is underneath.
• Do not bank low cards too eagerly. Foundations are one-way and there are eight of them. A 3 left in the tableau can host the 2 of its suit; sent up, it can host nothing. With two decks in play, patience with the low ranks pays.
• Expect to lose more than you win. Goodsol calls this an extremely difficult variant, and it is. Deals that cannot be won exist; recognising one early is a skill of its own.

Interchange in the Forty Thieves Family

Interchange is registered in the PySol Fan Club collection as a Forty Thieves game, and it earns the label: two decks, equal columns, eight foundations built up in suit, a stock turned one card at a time, and no redeal. What it contributes of its own is the deal. The board is built by dealing a face-up row, then a face-down row, three times over, and finishing with one more face-up row — which is exactly the alternation the name means.

Two further rules come straight from the same source and are worth stating. Only a King may fill a space: the collection wraps the tableau stacks with a King base rank, Goodsol ships "Kings fill spaces" as the default with "any card" offered as an easy setting, and other listings say it in words — "A King may move to an empty tableau, but no other cards may move to an empty tableau." And packed runs move as a unit, which is the concession that keeps seven-deep columns tractable.

There is no redeal here, and Goodsol supplies the cleanest citation for it while describing the game's sibling: "Unlimited is just like Interchange except that you get unlimited redeals instead of no redeals." A version of Interchange does circulate in which spaces take any card and one redeal is allowed — that is Goodsol's own "Interchange (Easy)" option travelling under the plain name, not a second reading of the game, and it is not followed here.

Its nearest relatives in this catalogue hide their cards differently. Emperor and Rank and File bury whole rows at the bottom of shallow four-deep columns, so the hidden cards are a single block to be dug through once. Indian Patience hides only its base row. Interchange interleaves them all the way up, which is a genuinely different problem. For the family's open-board classic, play Forty Thieves; for the same suit build with everything visible, Josephine.

One honest note on difficulty. Goodsol calls Interchange extremely difficult and PySolFC rates it mostly skill, but no published win rate for the game itself carries a method or a sample size, so this page quotes none. Its sibling Unlimited — the same board with unlimited redeals — is quoted around 34% in one place, which puts Interchange, with a single pass, well below that.