4x13 is played with a standard deck of 52 cards on a field 4 cards high
and 14 cards wide.  Initially, the deck is shuffled and laid out, face
up, in the rightmost 13 columns of the field.  The object is to get all
four suits in order, ace through king, left to right, in the leftmost
13 columns of the field.  This is done by moving cards around, each
move taking a card and placing it into one of the four empty spaces;
there thus will always be four empty spaces.

With three exceptions, to be described later, each empty space can
accept only one card, that one being the card the same suit as and one
higher in value than the card just to the left of the space.  Thus, if
the space is just to the right of the five of hearts, only the six of
hearts can go in that space.

The exceptions are spaces at the left edge of the field, which have no
card to their left, spaces following kings, for which there is no card
fitting the criterion, and spaces following other spaces, which also
have no card just to their left.  These are dealt with as follows:

- A space at the left edge of the field will accept any ace.  (No other
  spaces will accept aces.)

- A space just after a king is dead; it will not accept anything.

- A space just after another space is likewise unusable; it will not
  accept anything.  (It is not necessarily dead, though, as the space
  just to its left may be filled in.)

Thus, when all four spaces immediately follow kings or other spaces, no
moves are possible.  When this happens, all the cards that are not part
of consecutive runs starting with aces at the left margin are picked
up, shuffled, and laid out again, leaving one space after the last card
not picked up on each line.  This may be done only twice; the third
time all four spaces are unplayable, the game is over.  If at this
point all four suits are laid out in rows, the game is won.

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 are,
unfortunately, fixed: if the release is within 200ms of the press, or
if it's within 1 second and the pointer has mvoed less than a sixth of
a card in each dimension, it is considered to be a click.