The Tracker shows all the cells that are in the same row, column, or box as the cell the mouse is over. These cells cannot have the same digit as the current cell.

Pencil Marks show all the digits that are possibilities for each cell. When you are stuck, these can be quite helpful in pushing you along.

There are three Warnings settings:

• None - don't warn me.
• Obvious Errors - warn if I place a digit that conflicts with some other digit.
• All Errors - warn if the number I enter is wrong, even if there is no way for me to know that yet.

New Game starts a new Sudoku game of the difficulty selected in the box above it.