Glossary of Sudoku - Sudoku Variants

Sudoku Variants

The classic 9×9 Sudoku format can be generalized to an

N×N row-column grid partitioned into N regions, where each of the N rows, columns and regions have N cells and each of the N digits occur once in each row, column or region.

This accommodates variants by region size and shape, e.g. 6-cell rectangular regions (The N×N Sudoku grid is always square). For prime N, polyomino-shaped regions can be used. The requirement to use equal sized regions, or have the regions cover the grid entirely can also be relaxed.

Other variation types include additional value placement constraints, alternate cell symbols (e.g. letters), alternate mechanism for expressing the clues, and composition with overlapping grids. This page provides a simple list of variants. See Sudoku – Variants for details and additional variants.

For rectangular regions the row-column dimensions of the region may be used to describe the grid as whole, e.g. 3×2, since each of the grid side dimensions must be the product of row×column, e.g. for a 3×2 rectangular region, the grid must be 6×6. For rectangles of size N×1 or 1×N, the region is a row or column, and Sudoku becomes a Latin square.