Sudoku is a logic-based puzzle tracing its roots back to 19th century French newspapers. It began to gain widespread popularity in 1986 when it was published in Japan under the name Sudoku (meaning 'single number'). It first appeard in U.S. and U.K. newspapers in 2004.
Classic Sudoku is played on a 9x9 grid with 3x3 blocks, using the numbers 1 to 9. At Puzzletronic you can play four different grid sizes up to 25x25 and 3 levels of difficulty. You can also choose which symbols to use.
How to Play Sudoku
The objective of Sudoku is to complete a partially filled grid so that each symbol appears exactly once in each row, exactly once in each column and exactly once in each block.
Remember, incorrect cells will be indicated (in red) when any of the following errors occur:
- Any row contains the same symbol more than once
- Any column contains the same symbol more than once
- Any block contains the same symbol more than once
By selecting the New Puzzle option from the menu, the following puzzle variations may be chosen:
- Grid size: 4x4, 9x9 (classic), 16x16 or 25x25
- Difficulty: easy, medium or hard
By selecting the Settings option from the menu, the following may be chosen:
- Symbol set: choose from five symbol sets for more variation
- Sound effects: turn the sound effects on or off