Spielanleitung für Chaos Construction

Chaos Construction Sudoku (also called Uncoloured Irregular Sudoku) is a variant where the nine irregular regions are not shown at the start. Instead, only thick border segments are given — you must deduce the boundaries of the nine regions as part of solving the puzzle. Once you determine a region, it must contain 1–9 exactly once.

Thick line segments between cells mark regional boundaries. By following these boundaries and counting cells, you can begin to infer where each region begins and ends. A complete region always contains exactly nine cells. Cross-referencing digit placement constraints with possible region shapes is the core meta-solving step.

Yes. Every row, column, and the nine hidden irregular regions must each contain 1–9 exactly once. The regions are standard in size (9 cells each) and follow all the same rules as Irregular Sudoku — the only difference is that you must deduce the region boundaries as you go.

It is among the most challenging Sudoku variants. The region deduction layer adds significant complexity on top of standard Sudoku logic. Expert Chaos Construction puzzles are considered some of the hardest logic puzzles available. Even easy difficulty requires more concentration than most other variants.

Begin at corners and edges — border segments there are most constrained. Count cells along each segment to identify which regions are smallest and most bounded. Once you confirm a single full region, the digit constraints it introduces often help you trace the adjacent region boundaries.

Easy puzzles take 20–40 minutes. Medium puzzles run 40–75 minutes. Hard and expert puzzles can take well over 2 hours. The region deduction phase alone often takes longer than solving a complete standard Sudoku.