Variant Sudoku Guides
How the variants work and how to solve them. Each guide covers the rule, the techniques that crack it, and the questions newcomers ask most.
Killer Sudoku
Cages with target sums turn classic sudoku into an arithmetic puzzle. Includes a full cage combinations chart for every 2–5 cell sum.
Thermometer Sudoku
Digits climb from bulb to tip. Includes a range table giving the highest possible bulb and lowest possible tip for every thermometer length.
Arrow Sudoku
A circle holds the sum of the digits along its arrow. Includes a shaft-length table showing which arrows are even possible.
Kropki Sudoku
Kropki is Polish for “dots”. White marks consecutive digits, black a 1:2 ratio — small marks, big chains of logic.
X-Sudoku (Diagonal Sudoku)
Add two diagonals to a classic grid and the whole solve tightens. The friendliest entry point into variants.
Renban Sudoku
A renban line holds consecutive digits in any order. Includes a run table listing every set each line length can hold.
Between Line Sudoku
Digits on the line fall strictly between the two circled ends. Includes an endpoint table showing how many cells each gap can carry.
Anti-Knight Sudoku
No digit may repeat a chess knight's move away. Includes the eight-offset move map and the eliminations it creates.
Palindrome Sudoku
The line reads the same both ways, mirroring digits across its centre. Includes a pairing table for every line length.
German Whispers Sudoku
Neighbouring digits on the line differ by at least 5. Includes a partner table — and the reason 5 can never appear.
XV Sudoku
X marks a pair summing to 10, V marks a pair summing to 5. Includes the full pair table and the negative-constraint rule.
Mini Sudoku (4×4 and 6×6)
4×4 and 6×6 boards keep the variant rules but change the numbers. House totals, box shapes and a cheat sheet for every variant.
Put the guides into practice
Every variant in these guides, logic-checked, on 4×4, 6×6 and 9×9 boards, with new dailies every day. Free on iPhone, iPad and Android — no ads, no trackers.