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

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

**game number** - There are 32768 **game number**s 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 **layout**s dealt from **shuffle**s with a specific **level** eg 8x4-6

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

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.

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.

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.

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

- dfs - A Depth-First Search (or DFS) scan (the default method)
- patsolve - a no longer maintained 'other' solver written by Tom Holroyd that has been integrated into fc-solve
- a-star - A Best-First-Search scan
- random-dfs - A randomized DFS scan

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.

- Denny puts out the call, free@last takes on the challenge
- Unwinnable games debate
- "winnable" coming, level 10 results
- winnable format
- free@last intros WWC
- free@last posts full results
- cellmate adds to the data

- fc-solve found a solution

- the game is not solvable
- fc-solve couldn't solve it
- the attempt exceeded the '-mi' limit ( 6m )
- fc-solve crashed or was killed while trying to solve it

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