[This puzzle comes from the 2022 US Sudoku Grand Prix round. This Killer Sudoku was one of my favorite constructions even though I don’t write the style too often. I wanted to get a chain of “last-digit eight” clues into a loop in the grid, and managed to find cage sizes that made good use of 8, 18, 28, and 38 values in this grid. While a few given digits were needed to seed the solving path, that did not diminish the unique “eight” theme visually or logically.]
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Theme: Eight Ouroboros
Author/Opus: This is the 442nd puzzle from Thomas Snyder, aka Dr. Sudoku.
Rules: Standard Sudoku rules. Also, the sum of the digits in each cage must equal the value given in the upper-left corner of that cage. Digits cannot repeat inside a cage.
Estimated Difficulty: 3.5 stars