Backbone is two games played in sequence: free the Coccyx, then manage what the Backbone reveals.

How the layout is structured

Backbone Solitaire uses an anatomically themed layout with distinct named zones:

• The Backbone. A central column of reserve cards, initially face-down. The Backbone cards become accessible one by one from the top as the game progresses. But nothing in the Backbone can be touched until the Coccyx is freed.
• The Coccyx. A single card at the base of the Backbone. Playing the Coccyx to a foundation or to a Rib unlocks the entire Backbone. Until then, the Backbone is completely inaccessible.
• The Ribs. Eight tableau piles flanking the Backbone on each side. Ribs build downward by same suit. Only the top card of each Rib is accessible. Empty Ribs can accept any single card from the Backbone or waste, but not from other Ribs.
• Foundations. Eight piles (two per suit) building upward from Ace to King by suit.
• Stock and waste. Deals one card at a time. Two passes are permitted.

Phase one: liberating the Coccyx

The opening phase of every Backbone game has a single overriding goal: play the Coccyx card. The Coccyx can go to a foundation (if it is an Ace or fits the current foundation sequence) or to any Rib pile (if it is compatible with that Rib’s same-suit sequence). Either destination frees the Backbone.

The path to the Coccyx is almost never immediate. The Coccyx is blocked by Rib cards that prevent it from being reached. Specifically, you need to create a legal destination for the Coccyx, which requires:

1. Identifying the Coccyx’s rank and suit before making any moves.
2. Determining whether the Coccyx can go to a foundation immediately (is it an Ace, or does a foundation already need its rank and suit?).
3. If not, finding which Rib could accept it: specifically, which Rib holds a card one rank higher in the same suit as the Coccyx, or which Rib is empty.
4. Planning the sequence of moves to create that destination — and making those moves in the fewest steps.

Phase two: managing the open Backbone

Once the Coccyx is played, the top card of the Backbone becomes accessible. As each Backbone card is played (to a foundation or a Rib), the next Backbone card beneath it is revealed and becomes the new tip.

The challenge in this phase is that Backbone cards arrive in a fixed order that may not align with what the foundations need at each moment. Cards that cannot go to foundations must park in Ribs, and Ribs have limited capacity (only one card deep per Rib, same suit only).

• Route directly to foundations wherever possible. A Backbone card that fits a foundation should go there immediately. This clears the Backbone tip without consuming a Rib slot.
• Use Rib space for Backbone cards that will reach foundations soon.A card parked in a Rib with no near-term foundation path occupies a slot that a future Backbone card might urgently need.
• Keep at least one or two Ribs partially available as buffers.If all Ribs are full when an awkward Backbone card surfaces, the game may deadlock. Maintaining buffer capacity requires routing cards to foundations faster than they arrive from the Backbone.

Rib pile discipline

Ribs build downward by same suit, so a card placed in a Rib can only be reached again when everything above it has been played. Unlike FreeCell or games with open free cells, Ribs are one-deep per valid same-suit sequence. A poor placement early can strand a card for many moves.

The empty Rib rule is critical: only Backbone cards or waste cards may fill an empty Rib. A card from another Rib cannot move to an empty Rib. This means empty Ribs are reserved as entry points for new cards from the Backbone or stock, not as reorganization slots.

Stock and waste timing

The two-pass stock rule means every stock card is available twice at most. The waste top is always accessible, making the waste a one-card staging area that changes with each draw.

Use the stock to supply cards that the Backbone or Ribs are missing. Before drawing, check whether the waste top or any current Rib top can reach a foundation — clearing those first reduces the “pressure” on the system before adding a new card. Draw when no current play options exist, not before.

The combination of one-pass Backbone revelation and two-pass stock means the endgame often depends on the second stock pass. Cards that missed a foundation on pass one must be caught on pass two or they are lost. This makes first-pass routing decisions high stakes: send each waste card to the best destination it can reach on pass one.

What collapses a Backbone game

• Moving Rib cards before tracing the Coccyx path. Early Rib moves that do not serve Coccyx liberation consume moves and potentially rib space that would have been more valuable later.
• Filling empty Ribs with low-priority cards. The empty Rib rule (only Backbone or waste cards may enter) means an empty slot is a precious entry point. Using it for a card that could have gone on an existing Rib is wasteful.
• Not planning the Backbone reveal sequence. Some Backbone cards are immediately foundationable; others require Rib staging. Knowing several cards ahead in the Backbone allows you to prepare Rib space before an awkward card arrives.
• Exhausting both stock passes before the Backbone is fully cleared.If the stock runs out before the Backbone is exhausted, only Rib tops and the waste are available — a severely limited card set that can quickly deadlock.