Sudoku variant guides
Every variant on Sudoku Chaos has two guides: one that explains the rules with an example, and one that explains how to solve it, step by step. All of them are written for people who know ordinary sudoku and want to try something new. Pick a variant below.
Chaos and Double Chaos
Irregular jigsaw regions instead of 3×3 boxes. Double Chaos shows the same puzzle in two grids with different regions.
- What is chaos sudoku? The rules, and why the regions change how you solve.
- How to solve jigsaw sudoku Reading regions by colour, the law of leftovers, and solving both grids of a double chaos together.
Calcudoku
A small grid with no given digits. Each cage shows the sum, difference, product or quotient of its cells.
- What is calcudoku? The rules, with a solved 4×4 example.
- How to solve calcudoku Single-cell cages, row sums, and the order in which to work through the cages.
Thermo
Classic boxes plus thermometers. Along each thermometer the digits increase from the bulb to the tip.
- What is thermo sudoku? The rules and a first look at what a thermometer tells you.
- How to solve thermo sudoku Minimum and maximum per cell, long thermometers, bulbs and tips.
Kropki
Black and white dots between cells: black means one digit is double the other, white means consecutive. All dots are given.
- What is kropki sudoku? The rules, and what a missing dot tells you.
- How to solve kropki sudoku Black-dot chains, white-dot runs, and using the no-dot rule.
Killer
Classic boxes plus dashed cages. The digits in each cage add up to the number in its corner, and no digit repeats inside a cage.
- What is killer sudoku? The rules and the rule of 45.
- How to solve killer sudoku Cage combinations, innies and outies, and a solving order.
Sudoku X
Classic sudoku with one extra rule: both long diagonals also contain the digits 1 to 9 once.
- What is Sudoku X? The rules and the centre cell.
- How to solve Sudoku X The diagonal as a tenth unit, hidden singles on a diagonal, and box interactions.
Mix
Mix puzzles combine the variants above: chaos regions with thermometers or dots, or a calcudoku with thermometers. The guides of the ingredients apply. The title of each Mix puzzle says which ingredients it has.
Paper and print
- Free printable sheets Six PDF sheets every week, four puzzles each, with solutions.
- About the site and the books Who makes Sudoku Chaos, and the printed puzzle books.