Simple sudoku for Windows 8

SUDOKU game is played over a 9x9 grid, divided to 3x3 sub grids called "regions". Game begins with some of the grid cells already filled with numbers. The object of Sudoku is to fill the other empty cells with numbers between 1 and 9 (1 number only in each cell) according the following guidelines:
1. Number can appear only once on each row
2. Number can appear only once on each column:
3. Number can appear only once on each region