Klondike is played with a standard deck of 52 cards.  The playing area
is divided into three main sections: the stock area, displayed at the
upper left; the work area, displayed across the bottom; and the suit
piles, displayed at the top middle and right.

Initially, the layout has one card face-up on the leftmost work pile,
one face-down and one face-up on the next, two face-down and one
face-up on the third, etc, until the seventh work space has six
face-down and one face-up.  The suit piles are empty.  The remainder of
the deck is face-down in the left portion of the stock area.

Clicking on the face-down portion of the deck runs through it, three
cards at a time.  All three cards are visible, but only the topmost one
can be played.  When the face-down pile is exhausted, clicking on the
space where it was takes the pile of face-up cards and turns it over,
to be gone through again.  The rules allow this to be done only twice
(for a total of three runs through the deck); the game actually permits
an unlimited number of runs, but freezes the score when the deck is
turned over for the third time (see the section on scoring, below).

The objective is to get all the cards to the suit piles.  The suit
piles build up, from ace to king, in suit: a card can be moved to a
suit pile only when the card one lower is already there (except for
aces, which can always be moved up to start the piles).  Cards can be
moved to the suit piles from the work area or directly from the face-up
stock pile.  (It is also possible to move cards back from the suit
piles to the work area, but this is not often done.)

Cards can also be moved around in the work area, and taken from the
face-up stock pile to the work area.  In the work area, cards are built
up downwards in rank, from king down towards ace, by alternating
colors.  Thus, for example, the seven of spades could be placed on
either the eight of diamonds or the eight of hearts.  A whole pile of
cards can be moved at once; where it may be placed is controlled by the
card on the bottom of the stack being moved.  When a face-down card is
uncovered on one of the piles, it may be turned over by clicking on it;
when a work pile is completely cleared away, leaving a blank space, a
king (or a pile with a king on the bottom of it) may be placed there.
(Nothing else may be placed in an empty pile's space, and a pile with a
king on the bottom may not be placed anywhere else.)  It is possible to
move part of a pile, but is not useful except to get at a particular
suit to go on the suit piles, because that's the only context in which
the other card of the same denomination and color (which must be
present for the partial pile to be movable) won't do.

Scoring is based on the number of cards moved to the suit piles.  The
score for each game starts off at -52 (one for each card in the deck),
and has 5 added to it for each card moved to the suit piles.  (If cards
are moved off the suit piles, the score is adjusted to compensate, of
course.)  If the face-up stock pile is turned over for a third time,
the score freezes for the remainder of that game.  The game keeps track
of a total running score, the number of games played, and the score for
the current game.

When moving cards, either of two paradigms may be used:
click-move-click or push-move-release.  You can either click on the
thing to be moved, move it, and click to drop it, or you can press,
move, and release.  The game differentiates between the two based on
the length of time between the press and the (first or only) release,
and how far the pointer moves during that time.  These thresholds can
be tuned via the DragPixels, IgnoreDragTime, and MaxClickTime resources
(time values are in milliseconds).  There is also a shortcut: to move a
card to the appropriate suit pile you can double-click on it; the
double-click timeout is controlled by the DoubleClickIdle resource.

Double Klondike is just like Klondike except:

- Two decks of cards shuffled together are used.
- The initial layout has nine piles, not seven.
- There are eight suit piles.
- Scoring is simpler: one per card moved to the suit piles.