FreeCell is a solitaire card game played using the standard 52-card deck. It is fundamentally different from most solitaire games in that very few deals are unsolvable, and all cards are dealt face-up from the very beginning of the game. Although software implementations vary, most versions label the hands with a number (derived from the seed value used by the random number generator to shuffle the cards). Microsoft has included a FreeCell computer game with every release of the Windows operating system since 1995, greatly contributing to the game's popularity among users of personal computers, even leading to the creation of several websites devoted to FreeCell. Microsoft FreeCell is so definitive for many FreeCell players that many other software implementations strive for compatibility with its random number generator in order to replicate its numbered hands. Rules Construction and layout One standard 52-card deck is used. There are four open cells and four open foundations. Some alternative rules use between one and ten cells. Cards are dealt face-up into eight cascades, four of which comprise seven cards each and four of which comprise six cards each. Some alternate rules will use between four and ten cascades. Building during play The top card of each cascade begins a sequence. Tableaus must be built down by alternating colors. Foundations are built up by suit. The Foundations typically begin with Ace and are built up to King. Moves Any cell card or top card of any cascade may be moved to build on a tableau, or moved to an empty cell, an empty cascade, or its foundation. Complete or partial tableaus may be moved to build on existing tableaus, or moved to empty cascades, by recursively placing and removing cards through intermediate locations. Computer implementations often show this motion, but players using physical decks typically move the tableau at once. The maximum number of cards in a tableau that can be moved to another tableau equals the number of empty cells plus one, with that number doubling for each empty cascade: , where is the number of empty cascades and is the number of empty cells. The maximum number that can be moved to an empty cascade is . Victory The game is won after all cards are moved to their foundation piles. It is estimated that 99.999% of possible deals are solvable. Deal number 11982 from the Windows version of FreeCell is an