If you feel playing with automatic pencil marks almost makes the game too easy, I agree with you. And if you think clearing away manual pencil marks after placing a number on the board is just a plain pain, I agree with you. That is why we are introducing the all-new semi-automatic pencil mark mode.
It works like the manual pencil mark mode, with one huge difference: when a number is placed in a cell, all pencil marks of that number in the cell's row, column, sector and (if any) diagonals are removed. This is a great example of a small feature tweak that makes the game a lot easier to play.
Here are some screenshots of a cleared board to illustrate the new feature:
Set the pencil mark mode to semi-automatic:
Then add some pencil marks in the target cell's row, column, sector and diagonal just like in manual mode:
Place a number. Voila, the pencil marks are gone!