What are the basic rules of Sudoku?
Fill the board so no value repeats in a row, column, or box. The 16×16 stage uses 4×4 boxes and the symbols 1–9 and A–G for its sixteen values.
Progressive Sudoku Challenge
A mobile-first Sudoku game with 400 levels from 4×4 Easy to 16×16 Master, candidate notes, a daily puzzle, PDF printing, and account-free challenges.
Generating a unique-solution Sudoku…
❓ Sudoku Game FAQ
How many Sudoku puzzles are included?
The game includes 400 deterministic levels: 100 each for 4×4 Easy, 6×6 Junior, 9×9 Challenge, and 16×16 Master, plus a Daily Puzzle that changes each day.
Does every Sudoku puzzle have a unique solution?
Yes. Whenever a clue is removed, the generator runs a solver and keeps the empty cell only when exactly one solution remains.
Which input and solving aids are included?
The game provides candidate notes, hints, restart, erase, undo, an on-screen keypad, and physical keyboard input. In 16×16, use A–G for values 10–16. Selecting a cell highlights its row, column, box, and matching values, while conflicts turn red immediately.
Does the Daily Puzzle change every day?
Yes. The date and selected board size form a stable seed, so everyone opening the same stage on the same day receives the same board. It changes with the date and needs no stored puzzle database.
How can I print a puzzle or save it as a PDF?
Choose “Print / PDF” in the game controls. Your browser opens its print dialog, where you can print normally or choose “Save as PDF.” The print layout contains only the title, date, instructions, and a clean puzzle board.
Can I invite a Sudoku challenge without signing in?
Yes. After solving the puzzle, choose “Invite Challenge” to open the same share dialog used by the site header. The URL contains the compressed starting board and your time, so your friend needs no account or backend record.
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