How do you play Minesweeper?
Every square either hides a mine or doesn't. Open a safe square and it shows how many of the eight squares around it hold mines; a square with none around it opens its neighbours by itself. Open every safe square to win; open a mine and the game is over. Flags are your own marks for squares you know are mines.
Tap or click to open. To flag, right-click, hold your finger on the square, or switch on flag mode. Tapping a number that already has all its mines flagged opens every other square around it at once, which is called chording.
Why does no board here need a guess?
Because each board is checked before you see it. The mines are placed after your first tap, keeping that square and its neighbours clear, and the board is kept only if a solver can clear it from there by reasoning alone. In classic Minesweeper, mines are simply scattered at random, and some boards end with two squares nothing can tell apart. Of 300 boards dealt that way for each level, our solver could finish:
| Level | Board | Mines | Mines per square | Cleared without a guess |
|---|---|---|---|---|
| Beginner | 9 × 9 | 10 | 12% | 86% |
| Intermediate | 16 × 16 | 40 | 16% | 59% |
| Expert | 30 × 16 | 99 | 21% | 10% |
The others would have needed at least one guess, by the solver's moves (described below), so they are never dealt here. The sizes and mine counts are the three classic levels of Windows Minesweeper, the version by Robert Donner and Curt Johnson that came with Windows 3.1 in 1992.
How do you solve Minesweeper without guessing?
- Count closed squares. A 2 touching exactly two closed squares has a mine in both. A number whose mines are all flagged has no mine in its other squares.
- Compare two numbers. When a 1 and a 2 sit side by side along an edge, the 2's extra mine must be in the square only the 2 touches. Two numbers that share squares often settle the squares only one of them reaches; these are the 1-1 and 1-2 patterns players learn.
- Use the mine counter. Near the end, the mines left can be all that decides the last squares.
Those are the moves the solver uses to check every board. Solving Minesweeper in general is hard even for a computer: Richard Kaye proved in 2000 that telling whether a Minesweeper position is consistent is NP-complete.
How is your Minesweeper time calculated?
The clock starts on your first tap and stops on the last safe square. Next to your time is the board's 3BV (Bechtel's Board Benchmark Value): the fewest clicks that would clear it without flags, one for each patch of empty squares and one for each number no patch reaches. Your clicks count every square you opened and every chord; flags aren't counted. 3BV per second is the usual way players compare times across boards.
There is no rating: chording can clear a board in fewer clicks than its 3BV, so it isn't a true fewest. If you hit a mine, the result is the share of safe squares you had opened.
Can you play Minesweeper on a phone?
Yes. Hold a square to flag it, or switch on flag mode so that taps flag instead of open. On a phone held upright, the Expert board, 30 squares wide, is stood on its end so it fits; Intermediate and Expert squares are smaller than a fingertip there, so flag mode helps avoid mis-taps. For another grid of pure deduction, try Nonogram or Sudoku.