Chording โ clearing a whole neighbourhood with one double-click instead of picking off tiles individually โ is the difference between a slow board and a fast one. In most versions of the game it is a safe convenience: if your flags do not add up, the click simply does nothing.
That is not how it works in Minesweeper on this site. Here the double-click either clears the neighbourhood or ends the game on the spot, and the condition that decides which is not the one most players assume. This page sets out the actual rule, then covers what flags are and are not for.
The rule the game actually applies
When you double-click a tile in Minesweeper, the game counts how many neighbouring squares are mines that do not currently carry a flag. Then:
- Count is zero โ every hidden neighbour is revealed, cascading through any blanks. This is the payoff.
- Count is one or more โ every mine on the board detonates and you lose immediately.
Read that again, because the trap is in what is not checked. The game does not compare your flag count to the printed number. It does not verify that your flags are on the right squares. It asks one question only: is there an adjacent mine without a flag on it? If yes, you are dead.
What this means in practice
Three consequences follow, and all three catch people out.
A number that "looks satisfied" is not a green light. If a 2 has two flags beside it but one of those flags is on a safe square and a real mine sits unflagged in the third position, the number reads as satisfied and the double-click kills you. The display agrees with you; the game does not.
Wrong flags are survivable if the real mines are also flagged. The inverse is stranger. Suppose you flagged four squares around a 2 โ the two real mines plus two safe squares. There are no unflagged adjacent mines, so the double-click clears successfully, and the two harmless flags simply block those squares from being revealed. The clear works. Over-flagging is not punished; under-flagging is fatal.
The shortcut is live on hidden tiles too. The double-click handler is attached to every safe square on the board, not only to revealed ones. Double-clicking a hidden square with an unflagged mine beside it ends the game just as surely as double-clicking a revealed number would. Stray double-clicks in unexplored territory are one of the commonest ways to lose a board that was going well.
The safe chording procedure
Given that rule, chording is still worth using โ it is the fastest way to open resolved regions โ but it needs a discipline:
- Pick a revealed number on the frontier.
- Confirm that every mine you have deduced around it carries a flag. Not that the count matches โ that each deduced mine is flagged.
- Confirm you have not left an adjacent square undecided. An undecided square that turns out to be a mine is exactly the case that kills.
- Only then double-click.
The safest habit is to chord only on numbers where the surrounding neighbourhood is fully resolved โ every adjacent square is either revealed or flagged. In that state there is no undecided square left to surprise you, and the clear is guaranteed. If even one neighbour is still an open question, single-click the tiles you are sure about instead.
It is worth rehearsing this on the default 10×10 board in Minesweeper before taking it to a dense one. At 10% mine density, fully resolved pockets appear often and the cost of a mistake is a short game. At the expert layout's 20.6% the same mistake arrives later, after twenty minutes of careful work, which is a much more expensive way to learn the rule.
Flags: what they are for
A right-click places a flag in Minesweeper; a second right-click removes it. The counter at the top of the board tracks how many flags you have left, starting at the mine count for that difficulty, and you cannot place more flags than there are mines โ once the counter reaches zero, the next right-click does nothing.
That cap matters. If you flag speculatively and run out, you cannot mark a square you have since proved is a mine without first removing a flag elsewhere. Speculative flagging costs you the tool exactly when you need it.
What flags genuinely do:
- They make chording safe. This is the main reason to place them. A flag is what removes a mine from the fatal count.
- They protect against misclicks. A flagged square cannot be revealed by a left-click, so a mine you have marked cannot be opened by accident.
- They reduce bookkeeping. The outstanding count for a number โ the printed number minus adjacent flags โ is what every deduction in the patterns guide is stated in, and flags let you read it off the board instead of holding it in your head.
What flags do not do
They do not win the game. The victory check looks for any square still in the untouched state, and mines are never in that state โ they are marked as mines when the board is generated, before you click anything. Revealing every safe square wins, full stop, with zero flags placed.
They also do not validate anything. Placing a flag is a note to yourself. The game will happily let you flag a perfectly safe square, and will not tell you until the board fails to complete.
For timed runs this points to a lean approach: place flags only where you intend to chord, and clear everything else with single clicks. Flagging every deduced mine is thorough, but on a 480-square expert board it is a large amount of clicking that does not advance the win condition.
When not to chord at all
Three situations where the shortcut is not worth its risk:
Early opening. Before a substantial region is resolved, almost every neighbourhood contains an undecided square. There is nothing to gain and a whole board to lose.
Dense boards. On the expert layout mines occupy 20.6% of the grid, so undecided squares are more likely to be mines and the fatal branch fires more often. Chord only in fully resolved pockets there.
After a forced guess. A guess leaves you with a region you believe rather than know. Chording converts a wrong belief into an immediate loss instead of a recoverable mistake. Resolve the guess with single clicks until the numbers confirm it.
Recovering the speed you lose
If chording is riskier here than elsewhere, the compensating speed comes from the flood-fill. Clicking a square with no adjacent mines opens the whole connected blank region and the ring of numbers around it, in one action and with no risk at all. Chasing blanks is faster than chording and cannot kill you.
That is why the opening advice in how to play Minesweeper without guessing is to start in the bottom-right corner โ which on this board is guaranteed not to be a mine โ and then keep opening into wide untouched space rather than nibbling at a settled frontier. Blanks give you tiles by the dozen; chords give you a handful and can cost you everything.
Summary
The double-click clears a neighbourhood only when no adjacent mine is missing a flag, and detonates the board otherwise. It never checks whether your flags match the number, so a satisfied-looking number is not proof of safety and an over-flagged one is not a problem. Chord only on fully resolved neighbourhoods, keep flags for squares you have actually proved, and remember that flags are a tool rather than a win condition.
With that settled, the deductions that get a neighbourhood to fully resolved in the first place are the real skill, and they are laid out shape by shape in the Minesweeper patterns guide. The rules and controls are in how to play Minesweeper. When you are ready to try it, Minesweeper is a click away, and the rest of the logic shelf is in the best puzzle games.