Rules: Standard Sudoku rules (insert a number in the indicated range into each cell so that no number repeats in any “row” or bold region). Rows in Isodoku pass through opposite parallel sides of each quadrilateral; in other words, the rows bend across the surface of the apparent cube(s) to travel in a “straight” line.

Answer String: Enter the row marked “A”, followed by a comma, followed by the row marked “B”, starting at the arrow. This example has the key “34216758,21435867”.

(Brief) History of Isodoku: Descended from Sudoku and other geometric variations. Isodoku is a Japanese nanpure variation, created before the return of “Sudoku” to the West. (If you know more about the original author/publication of this style, please tell us). The English name is short for Isometric Sudoku, with the apparent 3d effect arising from an isometric projection; this genre is also sometimes called “3d Sudoku”.

History of this example: This Isodoku was written by Thomas Snyder for the 2012 US Sudoku Team Qualifier.

Sources for Isodoku: Follow this link for Isodoku puzzles on this website. If you are new to this puzzle type, here are our easiest Isodoku to get started on. More Isodoku can be found in Mutant Sudoku, Sudoku Masterpieces, and also in future titles by Grandmaster Puzzles.

Design rules for contributors: A Grandmaster Isodoku will have a unique solution that can be reached by logic alone. Generally, a Grandmaster Isodoku has a symmetric layout of given numbers, and the geometry of the puzzle should have all cells as part of complete “rows” and regions with few exceptions.