Scorpion Solitaire: Spider's engine with half the cards
Spider on this site deals 104 cards. Scorpion runs on the same engine with a single 52-card deck, and that halving changes the game's character. There are only four suits' worth of cards to complete, one of each card, and nothing to fall back on when a card is locked in the wrong place. You build down in suit, lift any face-up card with whatever sits on it, and fill gaps only with Kings.
Even perfect knowledge doesn't rescue most deals. A solver that knows all twelve face-down cards and the three stock cards won 12.9% of 3,000 deals (95% range 11.7%–14.1%) and proved 67.5% impossible (65.8%–69.2%), with 19.6% undecided. We have no two-deck Scorpion to compare, and no solver figure for Spider on this site's rules either, so we cannot put a like-for-like "one deck vs two" number on this engine.
At a glance: one deck on the Spider engine
| Measure (one 52-card deck) | Result | 95% range | Deals |
|---|---|---|---|
| Proven impossible, however you play | 67.5% | 65.8–69.2% | 3,000 |
| Won by a solver that sees every card | 12.9% | 11.7–14.1% | 3,000 |
| Undecided within 200,000 positions | 19.6% | 18.2–21.1% | 3,000 |
| At least one King starts face down | 65.2% | 63.4–66.9% | 3,000 |
| Solved with 2+ Kings face down | 14.0% | 11.5–16.8% | 645 |
| Solved with no King face down | 12.1% | 10.2–14.2% | 1,045 |
The true winnable share lies between 12.9% and 32.5%, and even that needs knowledge of hidden cards. Hidden Kings made little difference; the ranges overlap.
Why one copy of each card hurts here
Scorpion builds only in suit. With one deck, the 5 of clubs has exactly one card it can sit on: the 6 of clubs. If the 5 of clubs is stuck above the 4 of clubs in the same column, the only way to separate them is to move the 5 onto that single 6. If the 6 is buried under both, the deal is locked. In two-deck games such as Forty Thieves, there would be a second 6 of clubs to try. That is the kind of lock that makes two deals in three impossible here.
For contrast, Simple Simon, also one deck on the same engine but with any-suit building, was solved in 86.5% of 3,000 deals.
Scorpion rules on this site
- Deck: one standard 52-card deck.
- Tableau: seven columns of seven. The first four each have three cards face down; everything else is face up.
- Stock: the last three cards, dealt once, one to each of the first three columns, whenever you choose.
- Building: down by one rank in the same suit.
- Moving: any face-up card with everything on it, in order or not; only the lifted card must fit.
- Empty columns: Kings only.
- Suits: a full King-to-Ace suit is removed automatically; remove all four to win.
Playing a single deck with no spares
Scan for locks first
Look for a card sitting above a lower card of its own suit. Each one needs its single higher partner free. These tell you early whether a deal can go anywhere.
Reveal the twelve hidden cards
The solver's edge is knowing them. Turning them over early narrows that edge.
Move unsorted stacks with purpose
Lifting a whole mixed pile is the strongest move you have. Choose the pile that uncovers the card you most need.
Time the three-card deal
It helps the first three columns once. Use it when they are stuck, not by habit.
Walk away when it's locked
With about two deals in three impossible, a new deal is often the right move. Test a promising line with Undo first.
Playing on freecell-two-decks.com
Scorpion is free in any current browser on computer, tablet or phone, with no account. Hint, unlimited Undo, Restart and Auto Play are included, along with zoom, fullscreen, drag or tap moves, a counter for wins, time and moves, and sound and table-color settings.
How the figures were made
The freecell-two-decks.com team ran this test in September 2026 on this site's Scorpion rules.
- Rules from the code: seven columns of seven, three hidden cards in each of the first four, a three-card stock dealt once, same-suit building, any face-up card moving with its pile, Kings only in gaps, finished suits removed.
- A Python 3.11 program, standard library only, shared with Simple Simon.
- 3,000 numbered deals, seeds 1 to 3,000.
- A best-first solver that knows hidden cards and the stock, up to 200,000 positions per deal, so its wins are an upper limit.
- Impossible verdicts cross-checked with a separate brute-force program on the deals tested.
- No two-deck Scorpion and no published figure. Blake and Gent (2026) do not cover Scorpion.
- 95% ranges: Wilson score intervals.
Claude, an AI assistant by Anthropic, helped write and review the code and draft this page. Every figure comes from running the code, and the team checked them.
Scorpion questions
Why do I lose so often?
Most deals can't be won: 67.5% were proven impossible even seeing every card.
Is it Spider with one deck?
Close: same engine, but one deck, in-suit building, unordered pile moves and Kings-only gaps. Play Spider for the 104-card version.
Do hidden Kings ruin a deal?
Not measurably: 14.0% solved with two or more hidden, 12.1% with none.
What next?
Simple Simon is the friendlier one-deck cousin, and FreeCell Two Decks shows 104 open cards. All games are on the games page.
By Admin, freecell-two-decks.com (Forty Media). Research run September 2026.