Sixy Sudoku

A 6×6 sudoku is usually a children's puzzle. This one is not. Sixy Sudoku adds a fourth constraint to the familiar three, and that changes everything: the small grid stays easy to read, but the solving asks real work. Even the hardest Sixys take far less time than a 9×9 — without feeling easier. Invented by Peter Ritmeester and first published in The New York Times on July 21, 2019. How it works Place the digits 1 to 6 once in every row, every column, every bold-outlined area — and every colored area That last one is the extra layer. It is what makes Sixy Sudoku much harder en much more interesting. In the app 500 free puzzles across five difficulty levels, in two shapes: Regular and Wacky. Notes, timer, and your best times per level. More puzzle packs available as in-app purchases. Made by PZZL.com