# Read the board. Know the patterns.

Source: https://online-minesweeper.com/patterns

You don’t need to memorize hundreds of shapes. Start with counting, then learn how neighboring clues share information.

## Start with what a clue still needs.

Subtract the flags touching a clue from its number. The result is how many mines are still needed among its unflagged, unopened neighbors. If that result is zero, all those neighbors are safe. If it equals the number of those neighbors, they are all mines.

## The 1–2–1 edge pattern.

Imagine three clues in a row: 1, 2, 1. Their only unopened neighbors are the three squares immediately above them, with no other unknown squares touching the clues. The two outside squares must contain mines; the middle square is safe.

A row with mine, safe, mine directly above the clues 1, 2, 1

The middle 2 needs two mines. Putting a mine in the center unknown square would leave no legal place for the second mine without overfilling an outside 1. So the mines go on the outside.

**The boundary matters.** If other unopened squares also touch those clues, the same visible 1–2–1 numbers do not automatically prove this arrangement. Check every neighbor before applying a memorized pattern.

## Compare overlapping groups.

Suppose one clue needs one mine among squares A and B. Another clue needs one mine among A, B, and C. Since the one mine must already be in A or B, C is safe. This is subset reasoning, and it is one of the deductions used by our hint system.

## Use the total mine count.

If all mines have been correctly flagged, the remaining covered squares are safe. Conversely, if the number of remaining mines equals the number of covered, unflagged squares, all of those squares are mines. Flags are assumptions, so a mistaken flag can invalidate this reasoning.

## Chord carefully.

Once you know your flags are correct, click the number they satisfy to reveal its other neighbors. Chording turns a correct deduction into a fast move. It never replaces the deduction itself.

## When no obvious move appears.

Recheck flags, look for an overlooked clue at the edge, and compare overlapping groups. In no-guess mode, a logical path exists from the start. In classic mode, some positions really do require guessing; switch modes for a game that stays focused on deduction.