Chaos Construction
You must determine the region boundaries as part of solving
Chaos Construction is fully playable. Choose a difficulty and start solving.
The nine regions exist, but the puzzle will not show them to you: deducing their borders is half the solve. Thick edge fragments, cell counting, and digit logic feed each other until the map and the digits complete together. Among the toughest challenges on the site.
For the complete rules, worked examples and solving techniques, read the full How to Play Chaos Construction guide.
Like all Sudoku variants, Chaos Construction builds on the classic 9×9 foundation. Every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once. The variant constraint is added on top of these standard rules, never replacing them.
If you're new to Sudoku, start by learning the basic rules and techniques before attempting variants.
Techniques Useful for This Variant
| Technique | How it applies |
|---|---|
| Pencil Marks / Notes | Essential for tracking candidates alongside the variant constraint |
| Obvious Singles | Cells narrowed to one candidate by the combined constraints |
| Hidden Singles | Digits with only one valid cell in a unit after variant elimination |
| Pairs and Triples | Locked candidates exposed by the additional constraint |