What is Chaos Sudoku?

Chaos sudoku — also called jigsaw or irregular sudoku — plays by the same simple rules as classic sudoku, but with one twist that changes everything: the nine 3×3 boxes are gone, replaced by nine irregular, interlocking regions.

The rules haven't changed

The goal is exactly what you already know. Fill the 9×9 grid so that every row, every column and every region contains the digits 1 to 9 exactly once. No digit may repeat in a row, a column, or a region.

So what's different?

In classic sudoku the nine regions are always the same tidy 3×3 boxes. In chaos sudoku each region is an irregular jigsaw shape — a snake of nine cells that can bend and wander across the grid. You read the regions from their colours instead of counting to three, and that small change makes the logic feel fresh: the usual box-scanning habits no longer line up, so you have to look at the grid in a new way.

What is Double Chaos?

Double chaos takes it a step further. The same puzzle is shown in two grids side by side, each with a completely different region layout — but both share a single solution. Every digit you place appears in both grids at once, and the answer has to satisfy both sets of regions. Because each grid gives away different clues, you end up switching between them, using progress in one to unlock the other.

Is chaos sudoku harder?

It's a different kind of challenge rather than simply harder. Irregular regions remove the visual shortcuts of classic sudoku, but they also open up solving techniques that don't exist in the standard game — most famously the "law of leftovers." If you're new to it, our guide on how to solve jigsaw sudoku walks through the key strategies.