Sudoku Challenge

A Sudoku game that actually teaches. Every puzzle it generates is solvable by pure logic — guessing is never required — and Professor Owl explains the genuine next move whenever you ask, naming the technique instead of just filling the square.

Play 4×4, 6×6 and full 9×9 boards across five difficulties, from Easy to Extreme. The harder tiers are mined so they genuinely demand the deeper techniques rather than merely permitting them.

The techniques it teaches

Twenty-one, each with a worked diagram drawn from a real solved position and a practice puzzle where the pattern appears: naked and hidden singles, locked candidates, naked and hidden pairs, triples and quads, X-Wing, Swordfish and Jellyfish, XY-Wing and XYZ-Wing, unique rectangles, and the Phistomefel Ring.

How it works

Hints arrive in three steps — a nudge at the region, then the precise fact, then the cell — so you can take only as much help as you need. A free daily puzzle on every board, streaks, daily objectives, and a collection of themes, number styles and avatars that are all earned by playing and never sold. No adverts, ever.