No-Guess Minesweeper

How to play here

1. Choose a size. Each size keeps its own board, so you can switch and come back.
2. Open the cell with the ring. It holds no mine and neither do the cells around it, so a whole area opens.
3. Use the Flag tool on cells that must be mines and the Open tool on cells that must be safe. On a computer, the right mouse button or the F key places or removes a flag.
4. Stuck? Hint marks one cell that can be decided now and says which rule decides it.
5. New board builds another board of the same size. Restart closes every cell of the current board again and sets the time and the hint count back to 0.

Your board is saved in this browser after every move. It stays separate from the daily puzzle and never counts toward your streak.

When the board is cleared, Share result passes one line to the share menu of your device, or copies it: the size, your time and the hints used, with a link to this page at the same size. Boards are random, so the link does not open your board.

Board sizes

Beginner, intermediate and expert are the sizes of the Windows versions of Minesweeper; older versions used an 8 × 8 beginner board. The phone board is this site’s own size: nine columns fit a phone held upright, and it has the same share of mines as the daily board.

On a phone, the intermediate and expert boards have too many columns to fit at a size you can tap. Large cells, which is switched on for you in that case, keeps every cell big enough to tap; the board then scrolls sideways inside its frame while the page stays still.

• Minesweeper (video game) on Wikipedia

What a hint tells you

A hint frames one closed cell with a dashed line and underlines the numbers it reasons from, if any. The message below the board says whether the cell is safe or a mine, and which of the three rules proves it.

The hint trusts only what is certain: the open numbers and the mines it can prove. Your own flags are not taken as proof, so a flag in the wrong place cannot mislead it. A mine that the hint has proved counts only once you flag it; until then, the hint asks you to flag it. If the next safe cell carries one of your flags, the hint tells you to remove it.

Hints are counted and shown with your time. Nothing else changes: there is no penalty and no ranking.

Why no guess is needed

The generator places the mines at random, away from the start cell and its neighbours. A solver then plays the board from the start cell with three rules only: Rule 1, counting around one number; Rule 2, comparing two numbers, where every undecided cell of one is also next to the other; and Rule 3, counting the remaining mines. If these rules cannot open every safe cell, the layout is thrown away and a new one is tried.

Boards with a lower share of mines pass more often than expert boards. In one test we ran, 184 of 4,000 random expert layouts could be solved with the three rules: about 1 in 22. The generator tries up to 5,000 layouts and pauses between short batches so that the page stays responsive.

The three rules do not cover every possible chain of reasoning. Because only layouts that the three rules solve are kept, no board here needs more than these rules, and some layouts that a strong player could solve without guessing are thrown away too.

• The three rules, with examples
• Minesweeper rules

Example: comparing two numbers at the edge

Suppose that after a few moves the first three cells of row 1, starting in the top-left corner, are open and show 1, 2 and 1, while row 2 below them is still closed.

The 1 at row 1, column 1 touches only two closed cells: row 2, columns 1 and 2. One mine is among them. The 2 at row 1, column 2 touches those two cells and one more, row 2, column 3, and needs two mines. Exactly one of its mines is in the first two cells (the 1 says so), so row 2, column 3 is a mine.

This is Rule 2, comparing two numbers. When a hint uses this step, it frames row 2, column 3 and underlines the 1 and the 2. With that mine flagged, the 1 at row 1, column 3 has found its mine, so its other closed neighbours, such as row 2, columns 2 and 4, are safe: Rule 1.

Common mistakes

• Guessing when stuck. A certain move always exists on these boards; press Hint rather than tapping a cell at random.
• Forgetting the corner neighbours. A number counts all eight cells around it, including the diagonal ones.
• Opening around a number while one of its flags is wrong. Pressing an open number opens all its other neighbours once its flags match the number; this trusts your flags, so check them first.