The Easter Monster Falls

This post carries out the last remaining cluster merge trial, blue-to-purple, to its conclusion, and solves the Easter Monster with the help of limited patterns developed in this blog. A red-to-maroon cluster merge was verified in the post of April 1, which opened the cluster merge trials.

Seeing more monster aggravating action there, I choose the blue trial first, based on the blue-to-purple grid of the previous post.

EM bluepurp patsThe blue candidates knock out several of the red-to-maroon patterns enumerated in the cluster merging post of April 1, leaving orphans to remove (black diamonds). The blue 7r2c6 kills the solid and dotted orange 1-patterns, and the dashed and short dash orange 6-patterns, leaving only the solid one. Blue 7r4c8 kills the dot-long-dash red 1-pattern. Blue 7r6c3 kills the solid red 1-pattern. Blue 7r9c4 kills the solid and dot-dash red 6-patterns, leaving only the dashed red 6-pattern. The remaining red/orange 6-patterns spring traps(blue).

EM bluepurp redorangeFour 2-clues emerge: C2,S2=>N2, r6np39=>E2 .




The red/orange expansion traps four 8-candidates, setting the stage for an orange trial:


EM bluepurp orange trace

EM bluepurp orange trialAn inference diagram of the trial:

The inner core eventually concedes that the orange arrangement of its bv stepping stones is not going to work.



So it must be blue and red, or else it’s green.



EM bluepurp red boxlinesThe blue and red trial starts with two box lines, or you can mark it as a nice loop.









EM bluepurp bxl markingTrial marking the boxlines brings no contradictions, and when it is completed,

.  .  .



EM bluepurp final ANLthere is a 9393989 ANL that pulls out the sword, and the Easter Monster collapses. You’ll have no problem getting to the solution.

When the remote 39 pairs wouldn’t line up, I looked for a vulnerable 9-candidate and followed the XY-chain from one toxic end to the other. No searching required.



It was gratifying to see the pattern analysis and trials technique developed on the KrazyDad Insane review produce a solution of the Easter Monster that my sysudokie readers can readily follow. If you jumped ahead for a DIY finish, congratulations!

HMEMNext post begins a Sysudoku review of a report by Bob Hanson and Dave Marans on another puzzle also known to some – with good reason – as the Easter Monster. You can search it up, or perhaps you’d like to invest in the basic solving, with your checkpoint being their web article of March 12, 2008, titled Solution to the Easter Monster Puzzle: Formal Logic and Number Pair Chains.

Do you detect any similarities to the EM? I’m calling it the HM Easter Monster.

And whatever you celebrate, enjoy your Easter holiday!

About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
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2 Responses to The Easter Monster Falls

  1. Dennis says:

    When I was learning sudoku skills recently, I encountered the puzzle called the Easter Monster and through that I found your blogs. I haven’t finished reading all your posts yet but I’d like to share with you a new amazing skill that makes the opening shot much easier in this puzzle. The description and proof of this skill could be found here ( In the case of the EM, according to this skill, the inner region defined by r28c28(16 cells) has 8 counts of 34589 while the outer region (16 cells) has 8 counts of 1267, that means the rest of inner region contains only 1267 and the rest of outer region contains only 34568. These eliminations then lead to the founding of two triples of 126. In the case of the HM Easter Monster, try the regions defined by r68c18, and they also come with exactly 8/8 counts, and the rest of the opening shot is similar.

    • Sudent says:

      I’m very unclear on your regions, Dennis. The grid cells are divided between the inner and outer regions, right? A ring of 24 cells covered by r2, r8, c2, and c8 has an 8 count of givens of values 34589. The complement region of 57 cells has an 8 count of values 1267. But I don’t think ring geometry works on Sudoku constraints. Anyway, get back.

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