Minesweeper Glossary: Terms, Patterns and Definitions

The field

Field: The whole grid of squares, short for minefield. Also called the board. The Minesweeper Race field is 20 squares by 20, which makes 400 squares.
Square: One space on the field. It starts closed and hides either a mine or a safe space. Also called a cell or a tile.
Mine: What a square may hide. Opening one ends the attempt. The Minesweeper Race field has 60.
Clue: The number shown on an opened square. It counts the mines among that square’s neighbors and can be anything from 1 to 8.
Neighbors: The squares that touch a given square, diagonals included. A square in the middle of the field has eight, one on an edge has five and a corner has three.
Blank: An opened square with no mines among its neighbors, so it shows no number. Also called a zero or an empty square.
Opening: A connected area of blanks together with the ring of clues around it. Opening any blank reveals the whole area in one move.
Boundary: The line where opened clues meet closed squares. All deductions are made here. Also called the frontier or the edge of the opened area.

Open: To uncover a closed square, with a left click or a tap. Also called sweeping, revealing or clearing a square.
Flag: A marker you put on a closed square to record that it holds a mine. A flagged square can’t be opened until the flag is removed.
Flag mode: A LarkSpark control for touchscreens. While it is on, a tap places or removes a flag and doesn’t open the square.
Chord: Opening all the unflagged neighbors of a clue in one move, allowed when the clue already touches as many flags as its number. In Minesweeper Race you chord by tapping the opened number. The name comes from pressing both mouse buttons together.
Safe first click: The promise that the first square you open is never a mine. If a mine was there, the game quietly moves it to another square before the square opens.
Strike: Opening a mine. In Minesweeper Race a strike ends the attempt.
Mine count: The number of mines on the field. Most versions show it as a counter that goes down by one for each flag placed. Near the end of a game, comparing it with the closed squares that remain can settle a region the clues alone can’t.
Guess: Opening a square that the clues can’t prove safe. Random fields sometimes force one.
Fifty-fifty: A forced guess between two squares where exactly one holds a mine and no clue anywhere can tell them apart. Written 50:50 by many players.

Pattern: A common arrangement of clues along the boundary that has only one solution. Fast players recognize patterns on sight and don’t count them out.
1-1: Two 1s side by side, starting from a wall or the edge of the opened area, so that the first 1 touches two closed squares and the second touches the same two plus a third. The mine is in the first two, so the third square is safe.
1-2: A 1 beside a 2 along the boundary, where the 2 touches one closed square that the 1 doesn’t. That extra square is a mine. Ranking sites write it 1-2-X.
1-2-1: The clues 1, 2, 1 in a row facing three closed squares. The mines are under the two 1s and the square under the 2 is safe.
1-2-2-1: The clues 1, 2, 2, 1 in a row facing four closed squares. The mines are under the two 2s and the squares under the 1s are safe.
Reduction: Subtracting the mines you already know about from a clue to see the pattern underneath. A 3 that touches one flag acts like a 2, so the clues 2, 3, 2 with a flag beside each can turn out to be a 1-2-1.

Standard levels: The three boards of the classic Windows game, used for world rankings: Beginner at 8×8 with 10 mines, Intermediate at 16×16 with 40, and Expert at 30×16 with 99.
Density: The share of squares that hold mines. Minesweeper Race has 60 mines in 400 squares, or 15 percent, close to the classic beginner and intermediate boards. The expert board is about 21 percent.
3BV: The smallest number of left clicks that could clear a board: one for each opening and one for each clue that touches no opening. It measures how hard a board is. The full name is Bechtel’s Board Benchmark Value.
3BV per second: A board’s 3BV divided by the time taken to clear it. It measures solving speed in a way that allows for easy and hard boards. Written 3BV/s.
No-flag play: Clearing a board without placing a single flag, opening safe squares only. Written NF. A flag costs a click, so some of the fastest players use few or none.
No-guess board: A board built so that every square can be worked out by logic from the first opening onward. Minesweeper Race fields are generated at random and are not guaranteed to be no-guess.
Consistency problem: The question of whether any arrangement of mines fits a given set of clues. A paper published in 2000 proved it NP-complete, which means no fast general method for answering it is known.