Minesweeper

About Minesweeper

Minesweeper is a logic puzzle on a grid of closed squares, some of which hide mines. It has been around since the 1960s in one form or another and became famous as the game that came with every copy of Windows from 1992. This version is written from scratch for Kaamko. It has no adverts, no sign-up and no tracking of your games, and it works on a phone as well as a keyboard.

There are three sizes. Easy is 9 by 9 with 10 mines, Medium is 16 by 16 with 40 mines, and Hard is 30 by 16 with 99 mines. On a phone the Hard board scrolls sideways. Your fastest clear on each size is kept in this browser.

How to play Minesweeper

1. Open any square. The first square you open is always safe, and so are its neighbours, so the game starts with an open patch.
2. A number on an opened square counts the mines in the eight squares around it. A blank square has none, and its neighbours open by themselves.
3. When you are sure a closed square hides a mine, flag it: right click, press and hold on a phone, press F on a keyboard, or switch on Flag mode and tap.
4. Open a number that already has the right count of flags around it to open all its other neighbours at once.
5. Open every square that is not a mine to win. Open a mine and the round ends.

Reading the numbers

Most of the game is two patterns. If a 1 touches only one closed square, that square is a mine. If a number already has as many flags around it as its value, every other closed square around it is safe. Beyond that, look at pairs of numbers side by side: a 1 next to a 2 along a wall often settles which of three squares hold the mines. Guessing is sometimes forced, especially on Hard, but far less often than it feels.

Minesweeper is a favourite example in computer science courses too. Deciding whether a given board is consistent is a known NP-complete problem, which means it is as hard in general as the hardest puzzles computers can check quickly.