Best Free Sudoku Puzzle, Generator and Solver

Sudoku is a simple logic puzzle and number placement game, easy to learn, great for zoning your logic thinking while you play the game.

There is only one rule to completing a sudoku: each 3x3 box, each row and each column, must contain each of the digits from 1 to 9 without repetition (there are nine cells in every row, column and box). The puzzle begins with some cells already numbered. Your task is to fill in all the rest.

While the rule of Sudoku puzzle is pretty simple, but it can be quite a challenging puzzle to solve. Never give up too easily though, the good news is there are free and good programs to help you solve it. They help scan and keep track of possible digits for blank cells, provide filters and color markers to make solving even tricky puzzles much easier, faster and more interesting.

What's more? There are numerous hints and strategies to help play the game and solve the puzzle, such as the ones here and here. Or watch a series of video clips here.

Sudoku for Cross-Platform

HoDoKu is an open source program and runs on Windows, Linux or Mac. It allows you to generate sudoku puzzles in five different and configurable difficulty levels. It also includes a solver and an analyzer to help you solve the puzzles.

While playing the game, you can select to view a summary of solving techniques and the solution paths. When you click on a solution path, it highlights the steps on the corresponding grid to help you analyze the game. You can also opt for a practising mode, tick one or more techniques to be included in a new puzzle. All these features make HoDoKu not only a game to play but also a nice tool for learning and honing your skills in the game as well.

Other useful features include redo/undo steps, show candidates and invalid values, next vague or concrete hints and more. Puzzles can only be saved in a proprietary hsol format or a png image format for printing out, whereas import and export of games from/to other formats are not available.

SudokuBan is cross-platform (runs on Linux and Windows XP) and requires Python, GTK+, PyGTK to be installed.

What I like most is its clean design and intuitive interface—you just need to right click a cell and select the numbers from a small pop-up window. Better still, you can opt to restrict the numbers that are available for a cell.

With the program, you can create a random puzzle in a standard size of 3x3 box, or increase the size up to 6x6 box.

The games can be saved in a standard text format and opened later to continue the game.

While playing the game, you can check if the puzzle is valid or solvable, or let the program find a solution. On the downside, it has no undo/redo and printing functions.

Included as part of Simon Tatham's Portable Puzzle Collection, Solo by itself is a small portable program in 156 KB and runs on Windows, Mac OS X and Linux. It even has a Java interface for running in your browser online. You can click here and straight away play the game.

Other than the standard 3x3 box with various difficulty levels, it also provides other optional and custom types to suit your needs.

Even with this tiny program, you're not short changed—standard features including load, save and print games, redo or undo moves, right-click a cell to add a 'pencil mark', and solving puzzles are all supported.

Sudoku for Windows

With SuDoku Cracker, you can create a puzzle, play the game, or get a solution to the puzzle easily.

The program generates sudoku puzzles in high quality with a unique solution. It allows you to create a puzzle in any of 7 difficulty levels starting from 'very easy' to 'Super Sudoku'.

Besides playing the game, you can save or open a game in default sdk or text format, or print the puzzle to paper to fill in or share with others. Trying hard and can't solve the puzzle? The program can give a hint, solve the next step or even the whole puzzle instantly for you.

Many other features are included such as redo/undo moves, show or hide candidate values in blank cells, strike out a number, mark a cell, row, column or box in different colors, etc. Free registration of the program is required after installation.

Simple Sudoku creates challenging puzzles with 5 grades, from 'easy' to 'extreme'. It generates each puzzle randomly, so the selection is practically limitless.

The program has a keyboard and mouse friendly design with adjustable window sizes.

Similar to SuDoku Cracker, it helps scan what are possible digits for blank cells each time you enter a number, with a hint or even solution for the next number, covering almost all logical solutions for you. That's one of the helpful tools to help solve the puzzles—removing the drudgery but keeping the fun for the game.

Other features of the program include redo/undo moves, copy and paste puzzles to and from the clipboard, save, load or print completed or partially completed puzzles, etc. To save a game file in a text format, you need to add ".txt" to the file name.

If you need more varieties, Isanaki Sudoku is a good choice. Not only has it had a standard Sudoku mode, it allows you to switch over to a Wordoku mode easily, entering letters instead of numbers.

The program has 6 levels of difficulty, equipped with a generator and a solver using the brute-force technique and solving most of the hard Sudoku boards. It provides optional 9x9 or 16x16 boards which are configurable by users, but certain buttons in the 16x16 board go beyond the window if not maximized.

Other useful features include hints, redo/undo moves, show mistakes, highlight candidates, print multiple boards, saving and opening, import and export, plus a simple sound effect.

After downloading the zip file, extract it and run the executable directly.

Pure Sudoku has 4 levels of difficulty in gameplay, over 40 refreshing backgrounds, and contains 20,000 different sudoku puzzles, enough to play everyday for years. It automatically saves your game progress so that you can adjourn and return to the game anytime.

You can play full-screen or windowed, redo/undo moves, display any duplicate numbers entered, or get the solution to the puzzle with one-click.

On the downside, some other features such as hints, checks, or selectively saving or loading of games are only available with the paid version.

It is easy to start Total Sudoku—run the program, point at a blank cell and key in a number between 1 to 9. It comes with an attractive user interface and lets you automatically generate a new puzzle in any of 3 levels of difficulty ('easy', 'medium' or 'hard').

The program helps by coloring a cell green when you enter a digit correctly, or red if you've got it wrong, but it doesn't include a solver for you.

You can save a game in progress, so you can adjourn and come back whenever you want. Or you print the puzzle to paper to fill in.

Other than the above, you might want to try out another solver Gwerdy SuDoku Solver which uses logical methods to help find solutions to most puzzles. It retrieves all cell values at a press of the "Solve" button, or just a single cell digit each time you hit the "Hint" button. The default file format is .spf (sudoku puzzle file), but a text file can be loaded too. Alternatively, a "Load from text" option can be used to paste a sudoku puzzle copied to the clipboard.

Sudoku for Linux

KSudoku has a flexible user interface with configurable toolbars and themes.

With this program, you can choose a game in a standard size of 9x9 cells in numbers, or 16x16 and 25x25 cells in symbols, or in other shapes such as 3D Roxdoku, Samurai, 4x4, XSudoku and Jigsaw.

KSudoku provides a generator and solver, 5 levels of difficulty, allowing for saving and loading of games played. Hints, redo/undo are available but no printing of the game is supported.

The latest version 0.5 is included in the KDE Games Center and can be downloaded from Ubuntu Software Center as well.

Play Sudoku online

Other than Solo mentioned in this article, DKM Sudoku Online is well worth trying. It is almost as fully-featured as any of Sudoku download. Click 'Play Now' and go to 'Menu' to create a new puzzle in any of 4 levels. You can enter possible cell values manually in pencil mode, or let it scan for you. Other features such as undo last move, check for errors, hint, solve one or all cell values are included.

Alternatively, try Daily Sudoku with unlimited puzzles, online solver and hints.

You might want to check out these puzzle games too:

• Best Free Jigsaw Puzzle and Creator
• Best Free Match-3 Puzzle
• Best Free Crossword Puzzle (Stub only)

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