Autosave — Your current game is saved in your browser after every move. If you leave the page, you'll be able to resume exactly where you left off. Saves are kept for 7 days.
Settings ⚙️ — For advanced players, the gear at the top of the page turns on the ✏️ Auto button: it fills in every candidate of the grid at once, or only the cleaned candidates (locked candidates removed). This second option counts as a hint: the game won’t count towards “No hints”. You’ll also find large print there, for easier reading.
Hyper Sudoku stats — They are kept separate from your classic 9×9 sudoku stats and the other variants. They're stored locally in your browser and never sent to a server.
Hyper Sudoku: four extra squares
Hyper Sudoku, also known as Windoku, takes the classic 9×9 grid and adds a single rule: four extra 3×3 squares, tinted blue on the grid, must also contain the numbers 1 to 9, with no repeats. These squares are shifted one cell away from the boxes: each one overlaps four boxes at once.
That rule changes the way you play. A blue cell belongs to four groups at once (its row, its column, its box and its square). Every number you place in a blue square therefore tells you more than anywhere else, and the puzzles often start with fewer givens than a classic sudoku.
Sudoku-Land offers 3 levels (easy, medium, hard), notes mode, a step-by-step solver for hints, autosave, a dark theme and the ⚙️ Settings menu. Every puzzle has a single solution and cannot be solved without the blue squares: each one has been checked individually.
Hyper Sudoku rules
- Just like classic sudoku — every row, every column and every 3×3 box contains the numbers 1 to 9, once each.
- Plus the four blue squares — each one also contains the numbers 1 to 9, once each.
- On the grid — when you select a blue cell, its whole square lights up, just like its row, column and box.
Tips for solving a Hyper Sudoku
- Start with the blue squares — count the numbers already in each one: few are usually missing, and a square quickly gives a number away.
- Look where squares and boxes overlap — a blue square shares four cells with a corner box, two with two edge boxes and just one with the center box. If, in a box, a number can only go in the blue cells of a square, it disappears from the rest of that square (and vice versa).
- Cross squares, rows and columns — a blue square covers three rows and three columns. If, in a square, a number fits on a single row, it disappears from the rest of that row.
- Let your notes clean themselves — with the “Clear related notes” option in the ⚙️ menu, a correct number is also removed from the notes in its blue square.
All the grids on Sudoku-Land
Frequently asked questions
What is Hyper Sudoku?
It is a 9×9 sudoku with four extra 3×3 squares, tinted blue on the grid. On top of the rows, columns and boxes, each of these four squares must contain the numbers 1 to 9, with no repeats.
Why is it also called Windoku?
The four blue squares look like the panes of a window: hence the name Windoku. You may also see it called Hypersudoku or window sudoku.
Is Hyper Sudoku harder than classic sudoku?
Not necessarily. The blue squares add a constraint to respect, but they also give you more ways forward. At the same level, a Hyper Sudoku mostly asks you to remember to look at the blue squares. Sudoku-Land levels are graded with the same techniques as classic sudoku.
Does the Hint button work like in classic sudoku?
Yes: the Hint button opens a step-by-step solver that takes the blue squares into account. It explains each deduction on a small grid where the squares are tinted, and points to each square with a tiny drawing of where it sits in the grid. Reading the steps is free; only “Apply this move” uses up a hint.