

1. If you want to solve a sudoku, insert numbers 1 ~ 9 to make horizontal nine numbers include all nine numbers,
and to make vertical nine numbers include all nine numbers, and to make adjacent nine numbers in one color include all nine numbers. 2. Click a blank square or a red number square to insert, delete, or add a number. Blue number squares can not be changed. If you click a blank square or a red number square, a popup will appear. The white numbers in the popup are the numbers not in the clicked square. The red numbers in the popup are the numbers written in the clicked square. If you click a white number, the number will be written to the clicked square. If you click a red number, the number will be erased from the clicked square. Thus, you can write all the nine numbers together in one square if you want to for your convenience. You, however, must leave only one number in each square at last to solve sudoku. The number you've chosen will appear red in the square. 3. If you have written all the right numbers in all the squares, the timer will stop and the puzzle automatically tell you that you've solved it showing the elapsed time. 4. If you want to see the solution right now, click the leftmost button or key in Enter or AltC. If you want to wipe out the number you've written, click the middle button or key in AltW. If you want to enjoy another random sudoku, click the rightmost button or key in AltN. Invalid or broken puzzles which have multiple solutions are common on the net. This sudoku doesn'nt make such puzzles. Space key will press the button which has the focus. The Focus can be changed by Tab key or ShiftTab key forth and backward respectively. 
