Everything below is a straight answer about Sudoku by WizusLabs — no marketing gloss. If a question you have is not here, the how to play and difficulty guides go deeper, and the guides index covers the rest.
Cost, ads, and access
Is Sudoku by WizusLabs free?
Yes. Every puzzle, mode, and difficulty is free to play — nothing is gated behind a paywall. The free tier is supported by ads, and an optional Pro upgrade removes them, so if you never upgrade you still get the whole game.
Are there ads, and can I remove them?
The free tier is ad-supported, which is what keeps the whole game free for everyone. If you would rather solve without interruptions, the optional Pro upgrade removes the ads. The puzzles, modes, and features are identical whether or not you upgrade.
What does the Pro upgrade include?
Pro's main job is removing ads so you can solve without breaks. It is genuinely optional: the puzzles, all eight modes, every difficulty, and the daily challenge are already fully available on the free tier, so Pro is about comfort, not access.
Do I need an account or sign-up to play?
No. There is no account, no sign-up, and no login — open the game and start solving. Your progress is kept on your own device rather than in an online account.
Where and how you play
Can I play in a browser, or do I need to install an app?
You can play right in your browser at wizuslabs.com/sudoku, with nothing to install. That makes it easy to try a puzzle on any device before deciding whether you want it on your home screen.
Can I play offline, without wifi?
Yes. Every puzzle is generated on your device, so you can play with no connection at all — on a plane, underground, or anywhere with no signal. A connection is only used to serve ads on the free tier.
Where is my progress saved?
Locally, on your device. Your current puzzle, your history, and your settings live on the device itself rather than in an online account, which is also why no sign-up is required.
Puzzles, modes, and difficulty
What difficulty levels are there?
Six: Easy, Medium, Hard, Expert, Master, and Grandmaster. They are graded by how many starting digits you get and, more importantly, by which solving techniques each puzzle demands. The difficulty guide explains what each level asks of you.
What game modes and variants are included?
Eight modes: Classic 9×9, Mini 6×6, Killer, Irregular, X-Sudoku, Windoku, Even-Odd, and Large 12×12. The how-to-play guide describes each one and how it changes the way you solve.
Is there a killer sudoku mode?
Yes. Killer sudoku is one of the eight modes: the grid is overlaid with dashed cages that each carry a target sum, and no digit may repeat inside a cage. Our killer sudoku rules and strategy guide covers it in full.
Is there a daily challenge?
Yes, and it is free for everyone. The daily challenge gives every player the same puzzle each day — a quick, self-contained way to keep a habit without committing to a long session.
Does every puzzle have a solution, or will I ever have to guess?
Every puzzle has exactly one solution and is verified to be solvable by logic alone before you ever see it. You never have to guess: if you feel stuck, there is always a logical step you have not spotted yet.
Help while you solve
Are there hints if I get stuck?
Yes. Hints are available when you want a nudge, which makes a level slightly above your comfort zone a safe place to learn a new technique rather than a dead end.
Is there a mistake counter, and how many mistakes can I make?
In free play you can make up to five mistakes in a single puzzle before the round ends. It keeps the stakes gentle while still flagging slips as you make them, so you learn where your logic broke down.
Can I take notes or pencil marks?
Yes. Candidate notes — the small possibility digits you jot in a cell's corner — are built in, so you can track your eliminations without keeping a mental ledger. They become essential once you reach Hard and above.
Getting started and getting better
Is Sudoku by WizusLabs good for complete beginners?
Yes. Start on Easy, where simple scanning is enough, and lean on the built-in notes and the one-solution guarantee while you learn. The how-to-play guide walks through the rules from scratch.
How do I get better at sudoku?
Learn the named techniques and practise them one level above where you are comfortable. Start with how to play sudoku, work through the techniques guide and the glossary, then watch the whole ladder in action in our step-by-step worked solve.
Keep reading: solving a hard sudoku step by step · sudoku glossary · killer sudoku rules and strategy