Minesweeper · Complete guide
Minesweeper: how to play, and how to stop guessing
Every number is a constraint. Flags are optional, deduction is not — and the puzzle is formally as hard as any problem in NP.
Minesweeper hides a fixed number of mines under a grid. Open every square that is not a mine and you win; open one that is and you lose. Each number you uncover tells you exactly how many of its eight neighbours are mines — and that is the only information you ever get.
It is usually played badly, by clicking hopefully. Played properly it is a constraint-solving puzzle: subtract the flags you have already placed, check the two obvious cases, and then compare overlapping numbers. Most positions that look like a coin-flip are positions where two adjacent numbers have not been compared with each other.
A handful of patterns — 1-1 along a wall, 1-2-1, 1-2-2-1 — cover a large share of every board, and learning them as pictures rather than derivations is what makes fast players fast. The mine counter matters too: late in a board it constrains the whole frontier at once, and frequently resolves an "impossible" position outright.
And when a position genuinely is a guess, it usually still is not 50/50 — the untouched interior and the frontier rarely carry the same risk. That last distinction is the difference between finishing expert boards and not.
How to play
What the numbers mean, why flags are optional, what chording is, the three standard board sizes, and why your first click is always safe.
Where it comes from
A 1980s minefield game, a Microsoft bundle that taught a generation to use a mouse, and a proof that the puzzle is as hard as any problem in NP.
- Minesweeper's predecessors include Mined-Out (1983) and Relentless Logic (1985).
- The Microsoft version was written by Robert Donner and Curt Johnson and shipped in 1990.
- Bundling it with Windows taught millions of users precise mouse control, including right-click.
- Richard Kaye proved the Minesweeper consistency problem NP-complete in 2000.
How to win
The two rules that solve most squares, the 1-1, 1-2-1 and 1-2-2-1 patterns, the subtraction method, global mine counting, and how to guess well when a board genuinely forces it.
- Two rules solve most squares: if the flags match the number, the rest are safe; if the closed squares match, they are all mines.
- Learn 1-1, 1-2-1 and 1-2-2-1 as pictures — they appear constantly along edges.
- Compare overlapping numbers by subtraction; most "guesses" are uncompared pairs.
- The mine counter resolves endgames: remaining mines constrain the whole board at once.
Common questions
Do you have to flag all the mines to win?
No. The game ends when every non-mine square is open. Flags are bookkeeping, and fast players use them sparingly.
What is chording?
Clicking a number that already has the right count of flags around it, which opens all its remaining neighbours at once. It is the main speed technique — and it detonates the board if a flag is wrong.
Is the first click always safe?
In modern versions yes, and usually it opens a whole region rather than a single number.
Do you ever have to guess?
In the classic game, sometimes — a few positions are genuinely undetermined. No-guessing modes generate boards where logic is always sufficient.
Why is Minesweeper considered hard?
Because it is. Richard Kaye proved in 2000 that deciding whether a partially revealed board is consistent is NP-complete.
Guides
Play Minesweeper free, right now
No sign-up, no download — it runs in your browser against the computer, a friend on the same device, or a friend online.