FreeCell

FreeCell is the thinking player's solitaire. Every card is face up from the start, which removes luck almost entirely and replaces it with a genuine planning problem: you can see the whole deal, so any loss is one you can reconstruct and learn from.

The four free cells are what make it work. Each holds a single card, giving you just enough room to shuffle a blocked column apart — and not one card more than you need. The margin is deliberately tight, and the discipline of the game is spending that space carefully. It is also remarkable for being very nearly always solvable: with around 99.999% of deals winnable, sitting down to a game of FreeCell means sitting down to a puzzle that almost certainly has an answer.

All 52 cards are dealt face up into eight columns — four of seven cards, four of six — so nothing is hidden from the first move. Four free cells sit alongside, each holding exactly one card. Columns build down in alternating colours, foundations build each suit up from Ace, and any card can fill a column you empty. Strictly you move one card at a time, but with free cells and empty columns available most implementations will shift a whole ordered run for you, since the individual moves are mechanical.

Because nothing is face down, FreeCell is a puzzle rather than a gamble, and it can be played by looking before moving. The free cells are the constraint that matters: a card parked in a cell does nothing until you can unload it, and four occupied cells with no empty column is how most losses happen. Work out where the Aces are buried and plan the excavation before touching anything. Prize empty columns above free cells — a column holds a whole sequence, a cell holds one card. Wikipedia reports that around 99.999% of deals are solvable, roughly one unsolvable deal in 84,000; deal 11982 from the Microsoft version is the famous exception. Practically, if you lose a game of FreeCell you were beaten by the position rather than the shuffle.