The FreeCell Project classifies the difficulty of all games into a total of 8 levels. Most games fall into the "Unexplored" or "Feasible" categories, as they have not yet been played a sufficient number of times. A special commemorative certificate is issued to players who solve difficult games of "Hard" rank or higher. The criteria for determining each difficulty level are as follows.
A game that has not yet been solved. Too few players have attempted it to determine its difficulty, and it is uncertain if this FreeCell game is even solvable.
This FreeCell game has been solved, but by too few players to determine its difficulty. It is only known to be solvable.
This FreeCell game has been played four or more times, with a success rate of over 85.7% among players.
This FreeCell game has been played four or more times, with a success rate greater than 14.3% and less than or equal to 85.7%.
This FreeCell game has been played seven or more times and has a player success rate of 14.3% or less.
This FreeCell game has been played thirteen or more times and has a player success rate of 7.7% or less.
This FreeCell game has been played eighteen or more times and has a player success rate of 5.6% or less.
This FreeCell game has been played eighteen or more times and remains unsolved.