freecell.net (also known as NetCELL) is a well known implementation of freecell with a long history See About

Glossary

deck - standard collection of 52 playing cards, ace thru king, 4 suits

game number - There are 32768 game numbers 0 thru 32767

shuffle - (shuffled deck) game number is used as seed to a pseudo-random number generator which is used to select cards from a deck

level - (also called difficulty level or climate) is used to adjust the shuffle slightly so that on average lower level shuffles are easier to win eg an 8x4 level 6 game should be easier to win than the same 8x4 level 10 game

layout - (tableau) Columns x Freecells, the standard freecell layout being 8x4

deal - is dealing cards from a shuffle to a layout

variant - is a grouping of layouts dealt from shuffles with a specific level eg 8x4-6

n-sum - is a grouping of layouts by the sum of columns and freecells eg 8x4 is a 12-sum


Are all freecell deals on NetCELL winnable?

Answer: No

Over the years attempts have been made to identify the unwinnable games
Players organized to attempt to solve, or confirm unwinnable, all unwon deals. The more difficult games were escalated to the more skilled players.

How many NetCELL deals are there?

Answer: 3342336

For standard streak, there are 32768 game numbers and 6 levels (5 thru 10) so 196608 (6*32768) shuffles.
Each layout is dealt from the same set of shuffles. There are 10 column variations (4 thru 13). The number of freecells does not effect the deal.
So total deals is 1960800 (10 * 196608) (for standard streak play)
If you include levels 1 thru 5, 11, and 12 there are 3342336 (17 * 196608) deals.

Enter solver programs

FC-SOLVE is well known as a freecell game solver (which can also solve many other solitaire games)

fc-solve binaries are available to run on your windows or linux machine but these are limited to 10 columns and ?? freecells. The source code and build scripts are also available. It was necessary to rebuild fc-solve from source to increase the limits to get a fc-solve that can attempt to solve all of the NetCELL layouts.

Solving all the games

This effort is to run the solver program against all NetCell shuffles and variations

This requires a scripting effort to automate the running of fc-solve for all games for layouts with 4 thru 13 columns, n-sum 7 thru 16, and levels 1 thru 14
This adds up to 36241408 ( 79 * 14 * 32768 ) games to be played by the solver

Once the scripts were running it was just a great deal of patience waiting for the processing to complete.

4 solver methods were used on each game


So multiply that 36 million by 4. Patsolve took about 2.5 weeks to complete. Each of the others closer to 4 weeks.

I could have saved some time by not playing eg an 8x4 game if it had already been solved as 8x3, or if it had already been solved by a previous run, but i also collected a couple of other stats, eg moves, which required the runs. Just extra time, no extra effort.

Some relevant message threads


The results

Solved means
Unsolved can mean... note: 6x6 23218-9 is an example of a game solved by human but not by the fc-solve methods tried here (although yet another method was able to)

Data:
     
     
     

Filters:
Levels:
N-Sums:
Columns:
Freecells:

Show as:

Results from tbd



FC-SOLVE data

download merged results (used for this page) in csv format csv

csv files containing games solved flags for variants used to create merged results
use game number to index into that long string of 0's and 1's
4x 5x 6x 7x 8x 9x 10x 11x 12x 13x