Minesweeper guide: compare shared neighbors

The rules

Win by opening every non-mine cell. Flagging every mine is not required. A number counts mines in its eight surrounding cells, including diagonals. Opening a blank floods its connected blank area. Beginner, intermediate and expert use 9×9 (10) / 16×16 (40) / 30×16 (99) respectively.

Mines are placed on the first reveal. That cell and all its existing neighbors are protected, and timing begins then. Use right-click or the mobile flag mode to toggle flags. You cannot place more flags than the difficulty’s total mine count.

Getting started

Read the edge of the opened area first. Subtract confirmed neighboring mines from a clue and compare the remaining count with the closed cells. A 2 with exactly two closed neighbors makes both mines. Once a clue’s mines are all accounted for, its other neighbors are safe.

Compare the cells shared by adjacent clues to go beyond single-clue deductions. The first three diagrams show the top five rows of real 9×9 positions: two closed rows above three rows the engine can open. The topmost row does not touch the frontier clues, so compare their immediate closed neighbors.

The wall-side 1-1

With a wall-side 1 beside another 1, inspect the extra cell seen by the second clue. At r3c1 the clue sees the first two cells of row 2. Its neighbor sees those same cells plus r2c3, but still needs only one mine. Thus r2c3 is safe, even without deciding which shared cell contains the mine.

The 1-2-1 boundary

For 1-2-1, test why the cell above the middle clue cannot be a mine. If it were, both end clues would make their outer upper cells safe, leaving the 2 short. Therefore r2c1 and r2c3 are mines, and r2c2 is safe. The displayed clues and all their actual neighboring cells support that deduction.

The 1-2-2-1 boundary

Compare 1-2-2-1 from both ends to find its middle mines. Here the clues occupy row 3, columns 3 through 6. The left 1 and neighboring 2 differ by one: the extra cell seen only by the 2 must be a mine, and the cell seen only by the 1 must be safe. Mirror that reasoning from the right to force the other middle mine. The cells immediately outside the pair are then safe.

What a corner does not tell you

Do not choose between equally constrained cells just because they lie in a corner. The two flags here are confirmed mines. The 1 at r2c1 needs one mine among the two upper closed cells. Its neighboring 3 needs the same after subtracting two flags. Neither clue distinguishes the two choices. Look elsewhere for a proven move first.

Common mistakes

Check why each flag is correct before chording an open number. A matching flag count does not validate their locations, and a misplaced flag can make the chord open a real mine. Use fast controls to execute proven safe moves.

Trace actual neighbors before naming a pattern. One overlooked diagonal closed cell changes the shared sets. Recount those sets and remaining mine totals when rotating a pattern. After a loss, review the flag decision before the last click as well as the click itself.

Records and challenges on this site

The server reconstructs the starting board and first click, then replays reveals and flags to verify a winning record. Rankings are separate by difficulty, with shorter times first. There is no answer-revealing hint feature or hint time penalty.

When daily challenges are enabled and Minesweeper is selected, the starting conditions and first cell are shared. Daily dates use UTC. A safe first click does not imply a board that can always be solved without guessing.

Frequently asked questions