Klondike Solitaire

Klondike is a one-deck patience named after the Yukon gold rush of the late 1890s, and it is the game that shipped with Windows 3.0 in 1990 — which is how it became the most-played computer game in history. The rules are the ones on the solitaire page: build down in alternating colours in the tableau, build up in suit on the foundations, and fill empty columns with Kings only.

There is no single official score. The board here uses the most legible convention: 10 points for every card sitting on a foundation, plus 5 for every face-up card in the tableau. It rewards exactly the two things that win Klondike — banking cards and uncovering hidden ones — and it reaches 520 on a completed game.

On draw one, every card in the stock will eventually be available on its own. On draw three the stock is dealt in blocks of three and only the top card of each block can be played, so two thirds of the deck is hidden behind cards you may never be able to shift. Playing a waste card changes which cards surface on the next cycle — this is why experienced players cycle the stock before making tableau moves, to see the whole rotation first.

No. Some deals are provably dead from the start — three Kings buried under each other in the same column, for instance. Bjarnason, Fern and Tadepalli's Monte-Carlo planning study in 2009 was the first to put a firm floor under the number, at roughly 82%; Blake and Gent's exhaustive solver pinned it in 2019 at 81.956% ± 0.096% of draw-three deals, for a player who can already see the whole deck. Blind play is considerably worse. If you want a game where losing is always your own fault, play FreeCell.