Sudoku

 is a puzzle in Puzzledom.

How to play
The objective is to fill a 9x9 grid so that each column, each row, and each of the nine 3x3 boxes (also called blocks or regions) contains the digits from 1 to 9. A cell is the smallest block in the game. A row, column and region consists of 9 cells and the whole game consists of 81 cells.

Classic

 * Novice A
 * Novice B
 * Regular A
 * Regular B
 * Advanced
 * Expert
 * Master

Extension

 * Novice EX