Minesweeper - Measuring Board Difficulty
The difficulty of a given minesweeper board is often measured using the 3BV measure (stands for Bechtel's Board Benchmark Value).
The 3BV of a board is the total count of:
- openings of the board, i.e. regions of orthogonally or diagonally contiguous squares having no neighbouring mines, together with the immediately surrounding numbered squares
- numbered squares that are not part of any openings.
For example, in the illustrated example, there is one opening (shown by white borders) and there are seven further numbered squares (green dots), giving a 3BV rating of 8. Equivalently, it is the minimum number of single clicks required in typical implementations to reveal all of the mine-free squares.
3BV/s stands for 3BV per second.
Because the time that is needed to finish a Minesweeper board depends highly on the difficulty of the board, it may not be the best way to compare records. 3BV/s on the other hand does consider the difficulty of the Minesweeper board as well as the time needed to finish it. Among the best Minesweeper players, 3BV/s records are not nearly as important as time records, but they give a picture of how fast someone can play with regard to mouse-handling.
If flags are marked, it is possible to require fewer clicks than the 3BV of the respective board. Using only left clicks is called non-flagging (nf) whereas marking mines with right-clicks is called flagging-style.