Minesweeper

Your first minute on an Easy board

Pick Easy, the 9 by 9 board with 10 mines, and tap any square. Nothing can go wrong yet: the mines are only laid after that first tap, and they are kept away from the square you touched and all eight squares around it. That is why your opening tap always spills open a patch of blank squares ringed by numbers. The clock starts at that moment.

Now read the edge of that patch. Say you spot an open 2 that touches exactly two hidden squares. Both must be mines, so flag them with a right-click, or by holding your finger on each one. Next door sits an open 1, and one of your new flags is already touching it. That 1 is satisfied, so every other hidden square around it is safe. Instead of tapping each one, tap the 1 itself and they all open together.

That little loop, find a certainty, flag it, then clear around the numbers it satisfies, is the whole game in miniature. Medium and Hard simply ask you to run it more times, with less room to breathe.

Reading two numbers together

When no single number tells you anything, look at two neighbours side by side and compare what each one can see. Take an open 2 that touches three hidden squares, call them A, B and C. Right beside it, an open 1 touches only B and C. The 1 says exactly one mine hides in B or C. The 2 needs two mines among A, B and C, and B and C can only supply one, so A has to be a mine.

Flip it around too. If a 1 touches B and C and a neighbouring 1 touches A, B and C, the second 1’s mine is already accounted for in B or C, so A is safe. Most of the famous wall patterns are just this comparison done quickly, so practising it slowly on Easy pays off later.

Habits that quietly lose games

Almost every loss comes from one of a handful of habits rather than bad luck.

• Clicking in a rhythm. Once the board is opening nicely it is tempting to tap without checking. Give every square you open one honest reason.
• Trusting a flag you never proved. Tapping a number opens all its unflagged neighbours the moment the flag count matches, so one wrong flag turns a chord straight into a mine.
• Leaving a stray flag inside an open area. The automatic cascade of blank squares stops at flagged squares, and tapping a flagged square does nothing at all, so a mistaken flag can hide safe ground until you remove it.
• Ignoring the Mines counter. It is plain arithmetic, the board’s mine total with one knocked off for every flag, so it trusts you completely. A reading lower than you expect, or a minus sign, means at least one flag is surplus.
• Staring at one stuck corner. Logic travels: a square you settle somewhere else can open new numbers that work their way back to the spot that had you stuck.

Playing on a phone or tablet

On a touchscreen, a quick tap opens a square. Keep your finger down instead and, after a short 350 millisecond wait, a flag drops in or comes back out, with a tiny buzz on phones that support vibration. If your finger slides while holding, the flag is cancelled, so you can drag the board around on a small screen without dropping flags by accident.

Hard is a wide 30 by 16 grid. On a narrow phone the squares stop shrinking at a comfortable tapping size and the board scrolls sideways instead, so turning your phone to landscape usually shows more of it at once. If you get interrupted, the game saves your board and clock on this device, and the next visit picks up where you stopped. The save only lives until you begin another game: pressing the face button or picking a different board size clears it.

How your score is worked out

Losses are worth zero. For a win, the game subtracts your seconds from 1000, lifts anything under 100 back up to 100, and then counts the result once on Easy, twice on Medium and three times on Hard. A 45 second Easy win earns 955. A 3 minute Medium win earns 1,640. A 10 minute Hard win earns 1,200, which still beats the fastest possible Easy win, so working up to the bigger boards is the real way to climb.

Two small details are worth knowing. Planting a flag before your first reveal starts the clock too, so open a square first. And the Time display stops at 999, though the game keeps counting underneath. Each difficulty keeps its own best time on this device, and the end card lists it beside the time you just set. The board tells the rest of the story: after a win the smiley button above the grid puts on sunglasses and any mines you left unflagged get flagged for you, while after a loss every hidden mine is uncovered and a cross marks each flag you got wrong.

A little history

Minesweeper first reached Windows players in the Microsoft Entertainment Pack, then came built into Windows 3.1 in the early 1990s, which is how it ended up on so many office and school computers. The three board sizes here match the long-standing Windows Beginner, Intermediate and Expert grids. It has a serious side too: in 2000 the mathematician Richard Kaye showed that deciding whether a Minesweeper position is consistent is NP-complete, linking a humble desktop game to one of the biggest open questions in computer science.

Questions about Minesweeper