Sudoku: Classic Number Game

Sudoku is the number puzzle that needs no explaining and never stops being satisfying. Nine rows, nine columns, nine boxes, and every digit from 1 to 9 exactly once in each. That is the whole rule, and everything else is you working out where they go.

Tap a cell, tap a digit. Selecting a cell dims its row, column and box and lights up every other cell holding the same digit, which turns a hunt into a glance. Tap the pencil to jot candidates into a square, and placing a digit clears that candidate from every cell it can no longer live in.

EVERY GRID HAS EXACTLY ONE SOLUTION.

That sounds obvious and it is not. A sudoku with two valid solutions lets you fill a perfectly legal grid and still be told you are wrong, with nothing you could have done differently. Every board here is checked for uniqueness as it is built, on each clue removed, and checked again from scratch before it ships.

HOW THE GRIDS ARE GRADED:
- By technique, not by clue count. A grid with 26 clues that falls to simple scanning is easier than one with 30 that does not
- Each board is run through a solver that uses only the two simplest techniques, and graded by how far that gets
- The result is a ladder that actually climbs, from grids you can scan to grids that need pencil work from the start

WHAT YOU GET:
- Grids from gentle to genuinely hard, each one hand-checked by machine
- Pencil marks, with candidates cleared automatically as you place digits
- A hint that fills one correct cell when you are truly stuck
- Your own Sudoku Springs, a painted world that grows a landmark with every grid you finish
- Free to play, no sign-up, no timer breathing down your neck

Sudoku is for the daily-puzzle habit and for the long quiet evening alike. No pay-to-win, no paid currency, just numbers.

Pick a cell and start.