How to Use the Webgame

The puzzle is initially inactive. To start it, click on a button on the left selecting a difficulty level: Easy, Medium, Hard, Extra Hard. Once you have selected a difficulty level, your puzzle will be loaded.

You can also generate a new puzzle by clicking on one of the buttons labeled with different techniques. This option is explained below.

Digits which cannot be changed, appear in black, and digits which you enter in blue (unless a feature to check your progress is enabled, see below).

Moving Around

To enter your first number in the puzzle, you have to click on a cell, which then becomes selected. A selected cell is high-lighted in red, and any digits you type will be entered into it (unless a minicell also was selected, see below).

You can move between cells either by clicking on a new cell or by using the left, right, up and down arrow keys on your keyboard.

To select a minicell, you double click on it (if the cell is already selected single clicking is enough). Once the minicell is selected, any digits you type will be entered into the minicell. If you want to switch to the cell you have to click on it again.

You can move between minicells either by clicking on a new one or by using the left, right, up and down arrow keys on your keyboard.

Tip When Using Minicells

Since the minicells are so small, it might be helpful to enter a minicell-digit at the same position in all cells. This way it becomes easier to see in what cells a digit is a member of the candidate list.

Practice Makes Perfect

If you want to practice one particular technique you can also do that by clicking on one of the buttons labeled with the corresponding technique. This will generate a puzzle that is guaranteed to require that particular technique to be solved. Click here for an explanation of what the different techniques are.

Checking Your Progress

Whether you are stuck and need help, or you just do not want to make any obvious mistakes, you can use one of the options in the pull-down menu.

Check Validity:

Colors all digits that are violating any of the Sudoku rules red, based on the digits entered so far. This feature comes in very handy if you do not want any help, but are tired of making time consuming mistakes.

Check Correctness:

Colors all digits that are inconsistent with the final solution red.

Checking Your Answer

The button Check Solution checks the puzzle against the solution, and prints a congratulation message in case the puzzle has been successfully solved. If it has not, it will highlight the incorrect digits in red. If this button is pressed while there still are empty cells, its function is identical to the menu choice Check Correctness.

Reducing The Number Of Mistakes

When you are solving a Sudoku puzzle it is quite annoying to make mistakes, as it might require you to start over from the beginning again. One way of reducing the number of mistakes you make is as mentioned to use the Check Validity feature. Another way is to use our Dimming feature.

If you enable Dimming, clicking on a fixed (black) digit will dim out all other digits, thus helping you to concentrate on the selected one. The dimmed out digits come back if you click on a user-entered (blue) digit or empty cell.