How did Ruud rate his puzzles?
Well, I do not know but in an attempt to try to figure this out I have solved all his contest puzzles with JSudoku, the logical solver I currently use when generating puzzles. You can find the results
HERE in the files CE_JS_12b1.xls, CE_JS_13b1.xls, CS_JS_12b1.xls, CS_JS_13b1.xls, SAM_JS_12b1.xls and SAM_JS_13b1.xls.
Each line in the files looks like the image below, and the Rating column has an auto filter for selecting a specific rating.
If you download the files, you also have the Sudoku code for all of Ruud’s contest puzzles. In CS_JS_12b1.xls and CS_JS_13b1.xls the extra Clueless Specials #4a, #4b, #4c, #4d, Marlie Special, #6a, #7a, #10a, #14a, #18a/b and 37 Clueless are included.
To me it seems like his puzzles got easier over time. There are some early CS puzzles rated Moderate that have X-Wings and XY-Wings, and a Tough one with 6 X-Wings
I have received PMs and emails requesting puzzles, especially Samurais, with special solving techniques, especially X-Wings. Here is a summary of the number of Ruud’s contest puzzles having X-Wings so if you like this and have not solved them yet ………
Clueless Explosion: 12 (sometimes several)
Clueless Special: 27 (sometimes several)
Samurai: 8
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