Levels 1-50 are the "Original" collection.
Levels 51-58 are by author unknown.
Levels 59-98 come from XSokoban (levels 59 and 97 are easy versions of XSokoban levels 52 and 89, respectively).
Levels 99-190 are from Yoshio Murase, collections "handmade" and "autogenerated".
|"Sokoban" (1998) by William Fraser, level 53|
The eight levels "unknown" 51-58 are quite good, in old "Thinking Rabbit style". Especially interesting are the levels 53 (see image above) and 57.
Some time ago I wrote to William Fraser and I asked him if the puzzles 51-58 were his. This was his answer:
"I can't remember where levels 51 to 59 came from. The origional (first levels) cam from a spectrum program, and from 59 onwards came from a Japanese site (that I put a link to on the page). I think that up to level 59 came from the spectrum game (that would be about 20 years old by now), as I don't recall getting any levels elsewhere, but it's so long ago I could be wrong."
Therefore, levels 51-58 come from a Spectrum game. The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982.
In addition, says William Fraser in the "Readme" (May 2000) in your Java game: "I copied most of the levels from a 8 year old spectrum game that was in turn based on an earlier game." Thus, the Spectrum game must be in by 1990.
I have searched in "ZX Spectrum Museum", but I have not found any Sokoban game... Then, I have searched in "World of Spectrum", and I have found up to 7 versions of Sokoban prior to 2005.
|"Sokoban" by Hacker Chris, 1991, for ZX Spectrum|
The other puzzles by Chris 1-50 are the "Original" collection (taken from the IBM version of Spectrum HoloByte). Levels 51 and 52 is the level 18 of the "Original", repeated (#51 is an easy version).
I have not found who are the other five levels of Fraser 51-55.
To play online "Sokoban" by Hacker Chris, click here.
|"Sokoban" by Hacker Chris, level 54|
A curiosity. The puzzle of Evgeny Grigoriev, Grigr2001 #1 Bardak, first in the collection, seems to be a remodel of Fraser #57 (= Chris #54, see image above).
You can download the 8 levels from William Fraser here:
The question is: Who are the others 5 puzzles of Fraser 51-55? Can anybody provide more information?