Minesweeper Puzzle

Minesweeper here is a pencil puzzle. Some cells of the grid show a number from 0 to 8, and the blank cells hide the mines. You work out which blank cells are mines and which are safe, so that every number counts exactly the mines around it. You can play grids from 6×6 up to 10×10, and every puzzle here has exactly one solution that you can reach by logic, with no guessing.

Rules

The board is an n×n grid. Some cells are printed with a number. The rest are blank.

A number is how many mines sit in the eight cells around it: across, down, and diagonally. A cell on an edge or in a corner has fewer neighbours, and the count only covers the cells that exist. A numbered cell is never a mine, and its number never changes.

Every blank cell is either a mine or safe. The puzzle is solved when every blank cell is marked and every number has exactly that many mines beside it. There is no total mine count, and nothing opens or explodes when you mark a cell.

A dot marks a blank cell you have decided is safe. It does not show a number. It is only a note, but the grid is not finished until every blank cell holds a mine or a dot.

Controls

Click or tap a blank cell to cycle unknown, then mine, then safe, then unknown again. Shift-click cycles the other way. Right-click or a long-press places a mine, or takes it away. Selecting a number outlines the blank cells around it.

On a keyboard, the arrow keys move around the grid. X, M, F, or 1 places a mine. Period, S, O, or 2 marks the cell safe. Backspace, Delete, or 0 clears it. Space or Enter cycles forward. Shift with Space or Enter cycles backward.

A number that already has too many mines beside it, or whose neighbours are all marked with the wrong count, turns red at once. A number turns teal once every blank beside it is marked and the count is right. Press Hint for one step the rules already force, with a sentence saying why. Undo and Redo step through your moves, and Reset clears every mark. When the grid is right, the whole board turns teal.

Techniques

Easy grids follow from one number at a time:

• Zero: a 0 has no mine beside it, so every blank around it is safe.
• All mines: a number with exactly as many open blanks as its count needs a mine in each of them.
• Count closed: once a number has all its mines, the other blanks beside it are safe.

Medium grids also compare two numbers that share blank cells:

• Shared cells: if one number’s open blanks all sit inside another’s, the extra cells of the larger group hold the difference. That can make them all mines or all safe.

Hard grids need one more idea, still without guessing:

• One try: assume a blank is a mine, or safe, and drop the choice that cannot be finished.
• Small group: list the few ways a small group of blanks can be finished. A cell that is a mine in every way is a mine, and a cell that is safe in every way is safe.

Beginner tips

Start with the 0s, then with numbers in corners and along the edges. They have few neighbours, so they often settle several cells at once.

Mark safe cells as well as mines. A dot turns an open blank into a known one, and that is often what finishes the next number.

If you are new to Minesweeper as a puzzle, start with the daily 7×7 easy grid, and move up once zeros, full counts, and closed counts feel natural.