Tag Archives: Manuel Castillo

Bookends of the Only Hard


This post checkpoints the only sysudokie bypass casualty and the only sysudokie basic survivor, in this second review of Manuel Castillo’s Only Hard Sudoku collection. The report of my first review was posted 1 ½ years ago, March 29, 2016. … Continue reading

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A Well Hidden Pair in Only Hard 128


This begins a brief review of Manuel Castillo’s Only Hard Sudoku, preliminary to reviewing his more recent Only Extreme Sudoku. Both books are wordless collections of 400 puzzles, with identical formats. Thanks go to officers, members and guests of the … Continue reading

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AIC Slinks Finish Only Extreme 3


This post continues the finishing coloring cluster expansion in Castillo’s Only Extreme 3, via not-both testing of AIC slinks.  After extending the blue/green cluster in the North bank via AIC slink, we continue with a second AIC slink adjoining the … Continue reading

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Cluster Extension by Not-Both Trials


In this post and the next, the first puzzle of the Manuel Castillo Only Extreme Sudoku review, Only Extreme 3,  is taken ahead of the review of his Only Hard Sudoku. The reason is in the title. Rounding out the … Continue reading

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Castillo’s Only Hard Sudoku


This post concludes that Manual Castillo’s Only Hard Sudoku book is for those sysudokies who enjoy the bypass challenge, and are not expecting a to get to many advanced techniques. So many puzzle books, so little time. This relatively recent … Continue reading

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