FreeCell

Table of contents

1 Rules 2 History 3 Strategies 4 Culture 4.1 Automatic Solvers

Rules

FreeCell is a solitaire card game similar to Klondike. To play Freecell:

• Shuffle then deal the 52 cards face up in 8 columns with each card visible but only the end card of each column fully exposed. Four columns will have 7 cards, the other only 6.
• Apart from the columns, there are four single card free cells and four suit piles (foundations). The objective is to get all the cards into the foundations.
• Single exposed cards may be moved:
  • Column to column, placing the card on a card of the next rank and different colour suit. (E.G. Place a red 3 on a black 4.) (Aces are low.)
  • Column to freecell, any exposed card as long as there is an empty cell.
  • Freecell to Column, as column to column.
  • Column to suit home pile. Next card in order, starting with the Ace, ending with the King. Each suit is completely independent.
  • Freecell to suit home pile. As column to suit home pile.

The terms in italics are defined in solitaire terminology.

A game in progress

History

One of the oldest ancestor of FreeCell is Eight Off. In the June 1968 edition of Scientific American Martin Gardner described in his "Mathematical Games" column, a game by C. L. Baker that is similar to FreeCell, except that cards on the tableau are built by suit instead of by alternate colors. This variant is now called Baker's Game.

Paul Alfille changed Baker's Game by making cards build according to alternate colors, thus creating FreeCell. He implemented the first computerized version of it for the PLATO educational computer system in 1978. The game became popular mainly due to Jim Horne, who learned the game from the PLATO system and implemented the game as a full graphical version for Windows. This was eventually bundled along with several releases of Windows.

Today, there are many other FreeCell implementations for every modern system, some of them as part of Solitaire suites. However, it is estimated that as of 2003, the Microsoft version remains the most popular, despite the fact that it is very limited.

Strategies

A sequence of several cards with alternating colors can be moved at once by moving cards to vacant cells and/or temporarily placing them in empty columns. If the move involves temporarily placing a card in an empty column it is called a supermove in FreeCell terminology.

Cards can be safely moved to the foundations without a chance of being further used, if the value of the foundations of the different color are greater than the card face value minus 2, and the value of the other foundation of the same color is greater than the card face value minus 3.

Culture

FreeCell has spanned a great deal of culture around it. The most important information about it can be found in the Freecell FAQ which is maintained by Michael Keller. The Microsoft version could deal 32,000 numbered deals, and so most efforts were concentrated on analyzing their behavior.

The Internet FreeCell Project by Dave Ring, which was finished in October 1995, tried to analyze which of the Microsoft deals were solvable. Ring assigned 100 consecutive games chunks across volunteering human solvers and collected the games that they reported to be unsolvable, and assigned them to other people.

The only game in the Microsoft 32,000 that proved to be unsolvable by anybody (or any computerized solver) was No. 11,982.

Automatic Solvers

One of the passions of several Freecell enthusiasts was to construct computer programs that could automatically solve Freecell. Don Woods wrote a solver for Freecell and several similar games as early as 1997. This solver was later enhanced by William Callan and Adrian Ettlinger and was incorporated into their Freecell Pro software.

Another known solver is Patsolve of Tom Holroyd. Patsolve uses atomic moves, and since version 3.0 incorporated a weighting function based on the results of a genetic algorithm that made it much faster.

Shlomi Fish started his own solver starting of March 2000. This solver was simply dubbed Freecell Solver (which coupled with its many releases has the unfortunate effect of clogging the Google search for "freecell solver"). This solver is unusual because it can use meta-moves, groups of moves that aim to achieve a certain end.