FREECELL

'FreeCell' is a solitaire card game superficially similar to Klondike. However, it is thought of as a game of skill and strategy, not luck. Although implementations vary, all hands in common software versions of FreeCell have been beaten except for Game #11982.^[1], which has been proven to be unsolvable. This is in contrast to Klondike and other solitaire games where many hands are unwinnable even if the player's moves are flawless.

Contents

Rules

History

Strategies

Difficulty

Solvers

The Internet FreeCell Project

Windows versions

Forecell

References

External links

Rules

★ 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 others 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 in an empty column or on a card of the next rank and different colour suit (e.g. placing a red 3 on a black 4). Aces are low.

★
★ Column to free cell, placing an exposed card in an empty cell.

★
★ Free cell 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.

★
★ Free cell to suit home pile. As column to suit home pile.
The terms in italics are defined in solitaire terminology.

History

One of the oldest ancestors 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 rather than by alternate colors. This variant is now called Baker's Game. Freecell's origins may date back even further to 1945 and a Scandinavian game called Napoleon in St. Helena (not the game Napoleon at
St. Helena, also known as Forty Thieves). [1]
Paul Alfille changed Baker's Game by making cards build according to alternate colors, thus creating FreeCell. He implemented the first computerised version of it in the Tutor programming language for the PLATO educational computer system in 1978. Paul managed to display easily recognisable graphical images of playing cards on the 512×512 monochrome display on the PLATO systems.¹
This original FreeCell environment allowed games with 4–10 columns and 1–10 cells in addition to the standard 8×4 game. For each variant, the program stored a ranked list of the players with the longest winning streaks. There was also a tournament system that allowed people to compete to win difficult hand-picked deals. Paul Alfille describes this early FreeCell environment in more detail in an interview from 2000. [2]
The game gained worldwide popularity thanks to Jim Horne, who learned the game from the PLATO system and implemented a version of the game with color graphics for Windows. It was first included with Microsoft Win32s as a test program, then in Microsoft's Entertainment Pack Volume 2 and the later "best of microsoft entertainment pack". However Freecell remained relatively obscure until it was made a part of Windows 95 and has been included with every version of Windows since¹ (though Windows Vista Business Edition does not include it by default. It must be specifically installed.)
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 in player assistance features, such as retraction of moves. However, with the introduction of Windows Vista, the FreeCell implementation contains basic hints and unlimited move retraction.

Strategies

★ The basic strategy is to use the four free cells as temporary locations for cards: Cards should never (or seldom) be moved to a free cell without having a plan to move them away again.

★ A sequence of several cards with alternating colors can be moved at once by moving cards to vacant free 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.

★ Empty free cells and/or empty columns can also be used to sort cards in a column into the correct order. For example if one has the cards 10♦, 7♣, 6♦, 8♦, and 9♣ in a column and four empty free cells, one can move 7♣, 6♦, 8♦, and 9♣ to the free cells, and then back onto the 10♦ in the correct order.

★ A card can be safely moved to the foundations, without a chance of being needed later in the game, if either of the following conditions apply: (a) the values of the foundations of the different color are at least this card's face value minus 1; (b) the values of the foundations of the different color are at least this card's face value minus 2, and the value of the other foundation of the same color is at least this card's face value minus 3. For example, if the spade foundation pile currently goes up to 5♠, and the 6♠ card is available, it is safe to move this 6♠ to the spade pile as long as the other foundation piles either include 5♥ 5♦, or include 4♥ 4♦ 3♣.

★ Once a card has been moved to a foundation, it cannot be moved back into the playing area, so don't be too anxious to move too many cards of just one particular suit to a foundation (this is called "stacking up"). For example, if you start stacking up clubs (a black suit) in a foundation, you are going to end up with more red-suit cards than black-suit ones in the playing area, and this is going to cause you problems. However, ''it is generally safe to stack up two different-colour suits in tandem''. For example, if you have low-value diamonds and clubs that can be moved to the foundations, you may safely stack up these two suits immediately. Stacking up two suits of opposite colours will still leave an equal number of red-suit and black-suit cards in the playing area, so you won't be stuck with too many suits of a single colour.

★ Also, do not put all royals in the cells. For example, if you have in one column a black king, red queen, red jack, the other red jack, and a red king followed by an ace, wait before you go ahead and get the ace.

★ Do not go straight for the aces if they are all up top. Clear out some columns before you may go for the aces. You might get stuck with the cells full and no available moves, therefore ending the game.

★ There are three keys to winning freecell consistently: column management, space management, playability management.

★ Column management: The game starts with 4 columns of 7 cards and 4 columns of 6 cards. Almost every game will involve rearranging the columns to create one or more empty columns. Doing this requires making columns that are more efficient than the original 6 or 7 card columns. The most efficient column is a 12 card column that starts with a king and ends with a 2. Improving column efficiency requires starting new columns with an 8 or higher. Avoid starting new columns with anything lower than an 8.

★ Space management: Try to keep at least 2 open freecells and one empty column. Empty columns are usually more helpful than empty freecells.

★ Playability management:

★
★ Most freecell games will contain one or more playability problems. These problems typically include having both cards of the same color and rank buried or stacked. For example, game # 14405 has both black 7's buried at the top of the column. In addition to this problem both red 9's are stacked in the 7th column. Game # 14410 has both black 9's and both black 10's buried at the top of columns. It also has both black 4's, both red 5's, and both red 8's stacked. In the infamous game # 11982 both black aces and both red aces are buried, both black 5's, both black 7's, and both red 9's are stacked.

★
★ Try to avoid column play that results in both cards of the same color and rank in the same column.

★
★ Be aware of the playability consequences of moves. A strategy note above demonstrates how free cells can be used to sort cards into the correct order. Note, however, that the original order only requires 1 free cell to move to an open 10♥ and after they are sorted into the correct order they require 4 free cells to move to an open 10♥.

Difficulty

The FreeCell game, by allowing a finite number of possible games, can be trivially solved in polynomial time. Like Minesweeper, a generalized version of the FreeCell game with 4×''n'' cards is ''provably hard'' (NP-complete). This result was proven in 2000 and first published in 2001.^[2] The result implies that writing a computer algorithm that finds solutions for arbitrary FreeCell configurations of the generalized version quickly would be a major scientific breakthrough. A perfect FreeCell playing program running in polynomial time would earn the discoverer a $1,000,000 prize for solving one of the Clay Mathematics Institute's Millennium Prize problems. However, most researchers believe that no such efficient solution procedure exists.

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 Wilson 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 beginning in March 2000. This solver was
simply dubbed Freecell Solver.
Gary Campbell wrote a solver for FreeCell
which you can download and run in a DOS window.
This solver weighs in at 12 kilobytes, and is quite fast.
The most comprehensive list of solvers known contains links to other solvers. New solvers are constantly being written as part of assignments or projects for some university courses.

The Internet FreeCell Project

When Microsoft FreeCell became very popular during the 1990s it was not clear which of the 32,000 deals in the program were solvable. To clarify the situation, Dave Ring started The Internet FreeCell Project, took on the problem to try to solve all the deals using human solvers. 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. This project used the power of multiprocessing, where the processors were human brains, to quickly converge on the answer. The project was finished in October 1995, and only one game defied every human player's attempt: #11,982, which has been shown to be unsolvable by several exhaustive-search software solvers.

Windows versions

While there are actually 52!/8! (!=factorial), or approximately 2.00×10⁶³, possible games, some games may be similar to others because suits assigned to cards are arbitrary. When a card is black, for example, it may be assigned to clubs or spades.
The original Microsoft package includes 32,000, generated by a 15-bit random number seed. These games are known as the "Microsoft 32,000". Later versions of Microsoft FreeCell include more games, of which the original 32,000 are a subset.
The original Help file remains through modern Microsoft versions: "It is believed (although not proven) that every game is winnable." This was known at the time to be untrue in its strictest sense. Games numbered -1 and -2 were included as a kind of easter egg to demonstrate that there were some possible card combinations that clearly could not be won. Nevertheless it started a flurry of interest in the question of whether all of the Microsoft 32,000 could be beaten. Smart players could win most games most of the time, but that wasn’t proof either way.
In later implementations of FreeCell in Microsoft Windows, there are 1,000,000 games. Of these, 8 have been found to be unsolvable. They are games No. 11,982, No. 146,692, No. 186,216, No. 455,889, No. 495,505, No. 512,118, No. 517,776, and No. 781,948. This conclusion was arrived at by the consensus of several authors of FreeCell solvers. The solvers of both Danny A. Jones and Gary D. Campbell have been run through the first million FreeCell games and have found solutions to all but these eight. Several other solvers have also failed to produce solutions to these games.
One way to "win" at any Microsoft FreeCell game was added as a way to help the original software testers; one must push the following key combination of Ctrl-Shift-F10 (Doesn't work with Windows Vista) at any time during the game. When the dialog box appears on screen click 'Abort' to win, 'Retry' to lose, or 'Ignore' to cancel and continue playing the game as originally intended. Double-click any card for the results. However, this does not actually provide a correct solution to the game. Doing this combination on the unsolvable games however shows that there are decks that are not topped with Kings but instead with other cards, including Aces.
Another way is to open 'Select Game' and type -3 or -4 in the Select Game dialog box. When the game loads, simply drag an ace to the suit home pile, and the other cards will automatically follow onto the suit home pile, winning the game (Windows Vista only).

Forecell

'Forecell' is an uncommon variant of Freecell that appears on various software programs, including ''Soltrio Solitaire''.

References

1. One Down, 31,999 to Go: Surrendering to a Solitary Obsession (requires registration) Ellen Kaye
2. Malte Helmert, Complexity results for standard benchmark domains in planning, Artificial Intelligence Journal 143(2):219-262, 2003.

External links

★ World of Solitaire - FreeCell Free, web based solitaire that does not require Flash nor Java

★ FreeCell C#.NET- Screenshot

★ FreeCell Light A French FreeCell developed in Java

★ FreeCell FAQ

★ Freecell.net online competitive Freecell which replicates much of Paul Alfille's original PLATO Freecell environment with massive scores lists, statistics, and much more.

★ Freecell Solitaire rules and strategy tips

★ Play Freecell