Levels 1-50 are the original levels but you can make your own levels on the numbers 51-99 with the built-in level editor... i guess this Version you can download here just has 3 custom levels already done by the one who uploaded it or someone else.
I wonder if there is a way to convert the Standard-ASCII-format which most Sokoban-Clones use for Levels (see Wikipedia) to the old binary format the original used for custom-made levels... Anyone an idea? But propably not possible without knowing the source code of Sokoban.
perhaps you could write a program which would fake the inputs in the built-in Level-Editor to reconstruct the levels ingame you gave as ASCII-file beforehand...
Sokoban Directory looks quite confusing anyway... :wallbash: