WSC Playoff Puzzle 9/10: Clone Shape Sudoku by Joseph Howard

The last two closing puzzles of the World Sudoku Championship playoffs were very tricky, starting with this hybrid of Clone and Shape Sudoku by Joseph Howard.

Clone Shape Sudoku by Joseph Howard


or solve online (using our beta test of Penpa-Edit tools)

Theme: 8 Rings

Author/Opus: This is the 33rd puzzle from guest contributor Joseph Howard.

Rules: Combination of Shape and Clone Sudoku rules. Insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region. Also, there are some numbered shapes that must be put into the grid. Shapes can be rotated, but cannot be reflected. Each shape outside the grid must appear exactly once inside the grid. Also, all remaining shaded regions of the same shape (“clones”) must be able to be paired together to include the same numbers in the same positions.

Estimated Difficulty: 3.5 stars

Solution: PDF for all playoff puzzles.

Note: Follow this link for more variations of Sudoku.

  • erqnpgrq says:

    I must be missing or misunderstanding something here.

    Ng gur fgneg bs gur chmmyr, gurer ner sbhe 1f nyernql cynprq, cyhf nabgure gjb va gur funcrf cebivqrq, gbgnyyvat fvk; gurersber, gurer pna’g or n 1 va gur sbhe “pybarq” funcrf be gurer jbhyq or gra bs gurz va gbgny. Jr xabj gung gurer zhfg or n 1 va gur evtugzbfg funcr orpnhfr bs gur 1f va pbyhzaf 7 naq 8; guvf funcr pna’g or n pybar naq pna’g or gur 1234 funcr orpnhfr gurer’f nyernql n 3 va gung ertvba, fb vg zhfg or 1824 funcr, vgf bevragngvba qvpgngrq ol gur 2 va ebj 6. Ohg jvgu gung funcr cynprq, gurer’f abjurer sbe gur 1234 funcr gb tb.

    I don’t believe for a second that there will be a mistake in this puzzle so it must be my error, but I can’t see it at all.

    • Avatar photo drsudoku says:

      This is probably my error in trying to write out the rules for the web where we were able to refer to other puzzles at the WSC. If you had solved all the other WSC Clone Sudoku puzzles (as the competitors had before this), you would know that clones come in pairs and so I’ve taken an even greater effort now to clarify the instructions here that clones come in groups of two.

      Some of your reasoning seems to be working off all the clones being the same (a group of four), not groups of two.

  • erqnpgrq says:

    Thank you for the explanation, that was indeed my (mis-)reasoning.

  • skynet says:

    16:30. Wow ! This took quite a while and is challenging.

  • Anonymous says:

    Had to read the rules three times, but once I figured it out it was a great solve!

  • Amy Gould says:

    My version of the printed puzzle has different squares on the bottom than the solutions do. Is this a typo in my version of the puzzle (which is what you have above) or am I missing something?

    • Avatar photo drsudoku says:

      I don’t understand the question (the solution has all the info in the grid). But the version here is the valid puzzle and can be solved if you understand the rules with the shapes and the clones. The clones have to be identified when solving, so are not given outside the grid. Just the four shapes (out of eight total).

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