How to play
Select a number by clicking on it in the left column. The selected number will be highlighted.
Then you can click on the space where you wish to put that number.
You can delete a number by clicking on it with the same number.
You can overwrite an existing number, by clicking on it with another number.
Pre-set numbers, the ones that were shown at the start of the game, are written in white. Such numbers cannot be deleted or overwritten.
Numbers entered by the player are written in orange.
You are warned when an enterd number is in conflict with another, by red colours and some warning effects.
NOTE: just beacuse you are not warned immediately, it does not mean that the number entered is correct.