Simply put: What is Solitaire, and what are the best ones?

Every computer user knows at least one Solitaire game. You might prefer Klondike, or Canfield, or maybe one of the hundreds of lesser-known versions. Spend some time looking around, and familiarize yourself with the basic design pattern that represents “a solitaire game”.

What does it include?

• One or more decks of cards, perhaps with certain cards (Jokers, or low-value cards) removed.
• Two or more “stacks” in a tableau — generic positions where cards can be placed.
• Some rule for how to initialize the game: shuffling and initial placement. These involve what cards are face up, face down, whether they are known or hidden.
• A “round loop” that describes a set of one or more shifts of one or more substacks of cards between locations, possibly including moving some cards from the hidden undealt stack to a stack where they can be “used”. Allowed moves within a round may be governed by a complicated set of constraints involving position, suit, value, precedence and how many cards may be moved.
• A win condition, typically involving a particular state of cards being in particular order in particular stacks. For the purposes of this exercise (and possibly without loss of generality) the win condition may be taken as a single specific ordering of the entire set of cards in play, over the set of stacks.

[Did I miss much?]

So.

Limn the set of solitaire games. Present a formal, nonbrittle language in which any solitaire game may be written. By being nonbrittle, your language will allow random samples of the set of all feasible solitaire games to be made by simple aggregation (filling in words without the need for backtracking at any point), and will also allow one game to be transformed into another by local changes (substitution, deletion, swapping and insertion of words).

Bad solitaire, good solitaire. Present a suite of reasonable quantitative measures that will capture the complexity, difficulty, and entertainment value of any given solitaire game.

hint: Think about sudoku games. What makes a difficult game? What makes an entertaining game?