Frequently Asked Questions
We answer the most common questions about MundoSudoku and about sudoku itself.
Is it free to play on MundoSudoku?
Yes. All sudokus on MundoSudoku are completely free, with no limit on the number of games and no cost at all. You can play as much as you want.
Do I need to register or create an account?
No. You can start playing directly, without registering or providing any personal data. Your records and your game are saved in your own browser.
Does it work on mobile and tablet?
Yes. The site has a responsive design that works on computers, phones and tablets. On touch screens you'll see a comfortable number pad for entering numbers.
Do I need an internet connection to play?
You need a connection to open the site, but once a game is loaded you can keep playing normally. And if you'd rather play offline, you can download our PDF of 300 sudokus to print.
Do the sudokus always have a solution?
Yes. All our sudokus are generated with a guaranteed unique solution, so they can always be solved through pure logic, without ever needing to guess.
Are there different difficulty levels?
Yes. You can choose from four levels: Easy, Medium, Hard and Expert, to match the challenge to your experience and level up as you improve.
What is the Daily Sudoku?
It's a new puzzle every day, the same for all players. It changes at midnight and includes a countdown to the next challenge. You can try it on the Daily Sudoku page.
Can I save my game and continue it later?
Yes. Your game in progress is automatically saved in your browser, so you can close the site and continue later exactly where you left off.
Are my best times saved?
Yes. The site saves your records by difficulty level so you can compete with yourself and try to beat your own marks. You can check them on the Ranking page.
How does notes (pencil) mode work?
Notes mode lets you jot down several possible candidates in the same cell, just like you would with a pencil on paper, to solve harder sudokus without memorizing anything. Check out our guide on how to use notes mode.
Can I download sudokus to print?
Yes. We offer a free PDF with 300 sudokus of all levels, with their solutions at the end, ready to print and enjoy on paper.
How do you play Sudoku?
The goal is to fill the 9x9 grid with numbers 1 to 9 without repeating any in the same row, column or 3x3 block. You'll find the full explanation on our instructions page.