It's missing the double click on a number feature from minesweeper.
God, I used to be _really_ into Minesweeper.
One of the earliest games I made back in college was a 3D Minesweeper cube. I remember being really proud of one little detail – the detection and automatic resolution of ambiguous clues that would require guessing, which always annoyed the heck out of me in every other version of Minesweeper.
I also never knew it was called "chording", that's worth an explanation.