Sudoku is a puzzle with a grid containing nine large blocks. Each block is divided into its own matrix of nine cells. Each row, column and block must contain one and only one of the numbers from "1" to "9". When you’ve filled the entire grid, the puzzle is solved.
You can play sudoku with mouse or/and keyboard. With
arrow keys move through the grid, with numbers from
9 write in selected field,
T - toggle pen/pencil,
C to check the grid.