Minesweeper

How to play

Reveal all the non-mine cells to win. The number on a cell tells how many mines surround it: use it to deduce where they are. The first move is always safe.

Flags

Turn on 🚩 mode to mark cells you think hide a mine, so you don't tap them by mistake. Tap again to remove the flag.

The two rules that solve almost everything

The first: if the number on a square equals the covered squares around it, then they are all mines and can be flagged. The second: if the mines around a square are already all flagged, every other neighbouring square is safe and can be opened. With these two rules alone the vast majority of situations resolve.

The next step comes from looking at two numbers together: if a 1 and a 2 are adjacent, the squares lying only under the 2 and not under the 1 contain one more mine. It is the reasoning that unlocks closed corners, and that separates someone who finishes a medium grid from someone who stalls halfway.

The first click is never a mine

In modern versions of the game the grid is generated after the first click, precisely to guarantee you do not lose immediately, and in many the surrounding squares are kept clear too so that an area opens straight away. It is not a random kindness: without it, one game in ten would end on the first tap, and that would be maddening.

Hence a practical consequence: it is best to start from a corner or an edge. Edge squares have fewer neighbours, so the numbers that appear are lower and easier to read, and the initial opening tends to be wider.

When there is no safe move

It happens, and it is not the player's failing: some configurations are genuinely ambiguous, that is both possible arrangements of the mines are compatible with the visible numbers. In that case no deduction exists, only a probability, and a choice has to be made.

The right choice is not random: you count the possible arrangements and open the square with the lowest probability of holding a mine. A classic case is one where a neighbouring square is at fifty per cent and a distant one, in untouched territory, sits around twenty: the second is better, even though it looks less informative. The endgame is nearly always a gamble, and the statistics of the game prove it.

Why the ratio of mines to squares matters

Difficulty is not the number of mines but their density: in the classic levels it runs from about 12% for beginner to 20% for expert, and above twenty-five per cent grids become almost always unsolvable without guessing. It is why custom grids with too many mines are not harder, they are luckier.

The game dates from the early 1980s and became famous with Windows 3.1 in 1992, where it had been included to teach people to use the right mouse button. It is probably the way more people in the world have learned to make a formal logical deduction without realising it.

Nearby tools

For another logic game there is Connect 4 and for words Guess the word. For timing Online timer, and for scoring an evening Scoreboard.