Sudoku is a japanese mind game. You must find the way to place digits from 1 to 9 on a 9x9 grid. At the begining of the game, a few digits are given, and there is only one way to fill the grid correctly. Each digit must be placed in order to respect each of the following rules:
Traditionally, Sudoku is a solitary game. But on keyja.com, it's a 2-players game. Each player plays after the other until the grid is full. At the end, the player with the smallest count of errors wins the game.
In order to play, just click the square where to place a digit, and click a number.
Remember you can set the clock parameters in the game options.