Minesweeper

Classic Minesweeper with no-guess boards, chording, flags on touch and best times saved.

Game

Level

Setting up the board…

Play Minesweeper at Beginner, Intermediate and Expert, or on a board of your own size. Boards are no-guess by default: every one can be cleared by logic from a marked start cell, so a game is never lost to a coin flip. Switch it off for classic boards, where only the first click is safe.

The game runs in your browser. Your games, best times and stats stay on this device, and a game in progress carries on after a reload.

How to use it

Open every cell without a mine. A number says how many of the 8 cells around it hold mines; flag the ones you know, and open the rest. The counter on the left shows the mines less your flags, the timer on the right starts with the first cell you open, and the face between them starts a new game.

Mouse — a click does the chosen action, picked with the shovel (reveal, the default) and flag buttons under the board, and the right button does the other. A click on a number whose flags are all placed opens the cells around it (chording); so do the middle button and both buttons pressed together.
Touch — a tap does the chosen action and a long press the other, with a short vibration where the phone supports it. A tap on a number chords. A board wider than the screen scrolls sideways inside its frame.
Keyboard — the arrow keys move around the board, Space or Enter opens a cell (or chords on a number), F flags and C chords.

Chording with a wrong flag opens a mine and ends the game, as in the classic game; with too few or too many flags around the number, nothing happens. A game is won once every safe cell is open, flagged or not, and the mines left are flagged for you.

Daily is one no-guess Intermediate board a day, the same for everyone on the same date. A no-guess game's name, such as “Game #K3F9Q”, is its seed, and its shared link opens the same board for anyone. A won game shows its time, its 3BV and 3BV/s, and stats are kept per level, with classic boards apart: played, win %, current and best streak, best and average time. A game left for a new one after its first cell counts as played, not won.

Custom takes a width from 5 to 50, a height from 5 to 30, and from 1 mine up to the cells less 9, as the first click and its neighbours stay free. No-guess boards go up to 22% mines; a denser board is classic.

How the boards are made

A classic board is made at your first click: the mines are placed at random among every cell but the one you clicked and its neighbours, so the first click always opens an area. After that, some boards reach a point where two cells are equally likely to hide the mine, and only a guess goes on.

A no-guess board is made before the game, from its seed. A start cell is drawn with no mine around it, the mines are placed elsewhere, and a solver plays the board from that cell the way a person would. It uses three rules: a number whose flags are all found makes its other cells safe, and one whose covered cells are exactly the mines it lacks makes them all mines; two numbers that share cells limit each other (the 1-2-1 pattern); and once the mine count is used up, every covered cell is safe. If the solver gets stuck, the board is thrown away and the next one from the same seed is tried. Each attempt is drawn from the seed, so a seed always names the same board.

3BV (Bechtel's Board Benchmark Value) is the fewest clicks that clear a board without flags: one for each opening, the area a click on a 0 opens, and one for each number that borders no opening. 3BV divided by your time in seconds is 3BV/s, the speed players compare between boards of different difficulty.

Worked example

A no-guess Beginner board and its 3BV

Board (S start, * mine, . a 0): * 1 . . . . . . . 1 1 . . 1 1 1 . . . . . . 1 * 2 1 1 1 2 2 1 1 1 2 * 1 1 * * 1 . . 2 2 2 1 2 2 1 . S 1 * 2 . . . . . . 1 2 * . . . . . 1 2 4 3 . . . . . 1 * * *
3BV: 10
Cleared in 20 seconds: 0.50 3BV/s

A click on S opens its area of 0s with the numbers around it; every number left outside an opening takes one more click.

Levels

The standard levels and their share of mines

Level	Board	Mines	Mines per cell
Beginner	9 × 9	10	12.3%
Intermediate	16 × 16	40	15.6%
Expert	30 × 16	99	20.6%

Frequently asked questions

It is fairer rather than easier. The mines are as dense as on a classic board, and every cell still has to be worked out; what goes is the forced 50/50 at the end, where a classic game can be lost however well it was played. Best times are kept apart for classic boards, since a no-guess board never ends on a lucky guess.

The mines are placed at random, so nothing stops two cells from being told apart by no number at all: a 1 in a corner with two covered cells beside it is the usual case. Logic cannot decide it, so the game comes down to a coin flip. No-guess boards are checked by a solver before you play, so this never happens on them.