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Friday, October 19th, 2007

The classic Sudoku is played over a 9×9 grid divided into smaller 3×3 grids called “regions”. As you can see some grid cells already show a number (or generically a value or symbol).
Other versions feature different grid size and different values to fill the grid cells but, to avoid complicated explanations of the rules let’s just focus on the classic Sudoku sized 9×9 with numbers 1 to 9.

The objective of Sudoku is to fill the whole grid with numbers respecting this main rule

you can only use the same number once in each row, each column and in each of the 3×3 regions.

The Heracleum Sudoku Game Interface

On the top you can read how many given cells are already displayed on the starting grid.

Left-clicking on each cell of the grid will show all the values (numbers or letters in larger grids) in a popup menu: this will confirm the chosen value in the cell.

Right-clicking on each cell of the grid will show all the values in a popup menu: each selected value (with a tick on the left) will then appear as a small temporary value of the current cell. This comes in handy if you want to remember that a cell could contain only some values. Beginners could make a large use of this function while experienced players would use it only in tricky situations, to solve a blocking situation.

On the right (or bottom if the game area is vertical-wise) you can find three buttons: Timer, Options and Solution.


it usually displays the elapsed time since you started playing the game but it’s also a “Pause” button; click it to pause the game and the grid will disappear revealing the background.


clicking this button, the same right-clicking the empty background, will popup a small menu with definitely self-explaining commands:

  • Rendering quality: decrease graphics precision and details if your computer is running the applet too slow;
  • Hide Background: in case you find the background distracting;
  • Allow Controls: activating the backspace key will work as if you’re deleting backwards usual text (clears the cell values) or use the Mouse Wheel to roll the values up/down.


The correct numbers -in a transparent red colour- are overlapped on the game grid. Since the solution is semi-opaque you can easily tell if one of the number you placed is wrong, showing two different numbers one over the other.

All this buttons and sub-options can be toggled, activated and de-activated on every click.

5 Responses to “How to play Sudoku”

  1. Pat Says:

    The best place to learn how to play sudoku is Sudoku Learning Center.

    It has web based tutorials on all of the major solving techniques, such as x-wing, swordfish, coloring, etc. with custom designed puzzles that allow you to focus on one technique at a time. In addition it has a unique graphical interface to help you spot the technique if you get stumped.

    Try it out :)

  2. soduko fan Says:

    I enjoyed reading what you wrote, you should give a look for playing soduko puzzles online and competing with other players.

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  4. Sudoku Daddy Says:

    I do like a nice game of sudoku. It’s a great puzzle game for people of all ages, it helps enhance the memory and it can as well improve your problem solving expertise, everybody should complete at least one sudoku puzzle a day!

  5. 1algorithms Says:


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