How is Alternation different from Interchange?

Two rules. It builds down in alternating colours rather than down in suit, and any card may enter an empty column rather than only a King. The deal, the run move and the single pass through the stock are identical.

How is Alternation different from Breakwater?

Only the build rule: alternating colours here, any suit there. Both take any card into a space and both hide the same twenty-one cards. Breakwater is the easier of the two because each column top accepts twice as many cards.

Why do some sites call the rank-building game Alternations?

The name has been used for both readings. PySolFC registers the alternating-colour game as Alternation and the rank-building game as Breakwater, and this catalogue follows those registrations so that each name means one game.

Can any card go into a space?

Yes. The source gives Alternation's row stack an open base, and the play sites say the same. Interchange's king rule does not apply here.

How many cards are hidden, and when do they turn?

Twenty-one — three per column, in the second, fourth and sixth positions. Each turns face up automatically the moment the card covering it is moved away.

No. The 55 stock cards are turned once, one at a time, and the stock does not come back.

Alternation Solitaire - Play Online & 100% Free

Play Alternation Solitaire — Hidden Rows, Alternating Colours

Alternation takes the deal that gives Interchange its name — seven columns of seven with every second row face down — and builds it the way most players expect a solitaire to be built: down in alternating colours, a red 6 on a black 7. Any card may enter a space, a packed run moves as a unit, and the stock is turned once with no redeal. It sits between its two siblings in difficulty: looser than Interchange's suit build, stricter than Breakwater's rank build. Free in your browser, no sign-up.

How Do You Play Alternation?

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

Setup

Decks: two standard decks, 104 cards.
Tableau: seven columns of seven. Rows one, three, five and seven are face up; rows two, four and six are face down. Forty-nine cards, twenty-one hidden.
Foundations: eight, empty.
Stock: the remaining 55 cards, turned one at a time to a waste. No redeal.

Rules

Build tableau columns down in alternating colours: a red 6 on a black 7, a black 6 on a red 7.
A packed alternating-colour run moves as a unit.
Any card may enter an empty column.
A hidden card turns face up the moment the card on it is moved away.
Foundations build up by suit from the Ace and are one-way.
One card off the stock at a time, and no redeal.

Alternation Strategy

The colour rule halves what each column top will accept compared with Breakwater, so the hidden rows are harder to reach and the order you dig them in matters more.

Keep the column tops in both colours. Seven tops that are all black accept only red cards. Aim for a mix so that whatever the stock turns has somewhere to go.
Dig where the exposed card will be useful. Turning a hidden card is progress only if the card above it had somewhere to go; a move that exposes a card and strands the one you moved is a trade, not a gain.
Runs travel whole — use that to swap heads. Lift a run from a black 9 and set it on a red 10 elsewhere to free the card the 9 was covering. This is the move that opens the middle rows.
Open a space early and keep it open. Any card may enter, so a space is a universal parking bay. Empty a short column as soon as you can and fill it only to split a run at the card you need.
The stock is one pass. A waste card that fits should be played before a board move that can wait; a card you skip is gone unless the board changes for it later.

Alternation, Breakwater and Interchange

Three games share this deal in PySolFC's source, and they differ only in what may build on what and what may enter a space: Interchange builds in suit with Kings into spaces, Alternation in alternating colours with any card, Breakwater by rank with any card. Play sites tend to use the name Alternations for the rank-building version and note the colour rule as an option; this catalogue follows the registered source, so the colour game is Alternation and the rank game is Breakwater.

The alternating hidden rows are what make all three worth the trouble. Unlike a Klondike staircase, every column here hides the same number of cards at the same depths, so the game is about choosing an order rather than clearing the shallow columns first.

Like every game in this family here, the first stock card is left for you to turn rather than dealt to the waste at the start.