Make sure to put all the numbers 1 to 9 in 3x3 blocks surrounded by rows, columns and bold lines. Operation is the top arrow button, select the game, press the play button. You can enter by touching an empty place and then touching a number. To erase, touch the number of the place you want to erase. You can not enter an incorrect number. In that case, the ad will be displayed. If you want to interrupt on the way, you can exit as it is. Since the contents up to the middle are saved, it is possible to resume. There are 5 difficulty levels. There are 2000 problems. Since the questioning order is random, please try to skip difficult problems.