The first click is always safe because any mine is moved to the top left corner or nearest empty square to its right of it. This means the top left corner gives fewer openings than the other corners. It also means fewer openings result from the edge and middle squares touching the top left corner.
- The biggest openings occur in the very center of the board and decrease as you approach edges.
- The biggest openings from clicking on an edge are in the middle and decrease as you approach corners.