AB-Sudoku

So you want to play Sudoku. The rules are that a number appears only once in either a row or a column or a square of nine numbers. Squares are outlined.. The software is really easy to use. Choose a game under EnterData-Start a Set or fill in numbers from any puzzle that you want to work on. After all numbers are entered don`t forget to click on Enter Data-Done with entering Data as this defines the set of original numbers. Right Click shows the rows, columns, and the square (RCS) that are to be checked when a number is entered. You cannot violate the basic Sudoku rule and enter a number twice in this area. You pick up the number you want to enter from the yellow row. Or pick up an Erase. Under the Tools tab you can choose to switch the RCS-highlighting off. You can also choose to get some hints (see right screenshot) and possible numbers will pop up on the top of a numbers Box. If only a single choice remains that Little number is shown in red. With choosing "Maximal Help" additional number-selection rules are applied.The Green Go Back button allows you to step back through your filled in numbers (and you can have AB-Sudoku solve it for you).