Mr B has created a bit of a stir at the chess club by bringing along a fiendish “chessmen puzzle”. He and I both like chess, but we both like other board games and also puzzles. (An abstract strategy board game is really a way of setting and solving puzzles competitively.)
The ‘chessmen’ puzzle is illustrated below
and is an example of a whole group of puzzles which are known by the name of Klotski (like the Polish word for blocks). Here’s one with playing cards rather than chess pieces:
There’s an excellent Wikipedia article about Klotski puzzles:
https://en.wikipedia.org/wiki/Klotski
You will see that there is an obvious similarity but also some variations. This one marked with chess pieces and in that formation is not so common.
The version known in French as the Red Donkey is the most common sort of puzzle of the Klotski type, which has four of the vertical two-by-one pieces, whereas Mr B’s chessmen puzzle has two vertical two-by-one pieces and two horizontal two-by-one pieces. I think the former is the harder arrangement — certainly takes more moves, and took me longer!
https://fr.wikipedia.org/wiki/L%27%C3%82ne_rouge
You can find other examples of these Klotski puzzles: there’s a Chinese version called Huarong Pass, which has got a long history and some variations of its own. A story has been attached to the puzzle about an army general who finds his way blocked. The standard arrangement is with four vertical 2×1 pieces.
In Japan, the puzzle is known as ‘girl in a box’ or ‘daughter in the house’ – the story is of an overprotected young woman who is not allowed out much, and manages to escape the family home. (I can only advise you now never to do a web search for “Japanese girl in a box” – you have been warned — but hakoiri musume is safe enough.)
Here as an example of the puzzle, and a version marked with Shogi pieces:
The Shogi version could be set up the same layout as Mr.B’s puzzle. If you have one of these puzzles you can create more using the same pieces:
https://chinesepuzzles.org/huarong-pass-sliding-block-puzzle/
The cheapest and most common Klotski puzzle I can find online is the classic four-vertical-one-horixontal:
You can play Klotski in its classic form here:
https://klotski.online/pages/online-klotski.html (150 different puzzles!)
https://klotskipuzzle.com/en/ (with musical accompaniment…).
There is a general Klotki puzzle solver here:
https://samrroyall.github.io/klotski-solver/
See it in action:
More about Klotski:
Martin Gardner (1964) Mathematical Games: The hypnotic fascination of sliding-block puzzles. Scientific American (Feb).
Reprinted in his 6th collection of columns.
If you solve all these, try the Rush Hour puzzle game:
