How to read these patterns
Each diagram assumes the displayed clues have no other covered neighbors. “Mine” marks a forced mine, “Safe” marks a forced safe square, and a question mark means the pattern alone does not decide that square.
Subtract any already flagged mines from a clue before matching a pattern. A displayed 2 touching one confirmed mine behaves like a remaining 1.
The two edge patterns
Satisfied clues
If a clue already touches the number of mines it requires, every other covered neighbor is safe. This is the fastest deduction on most boards and often starts a chain of reveals.
Full clues
If a clue still needs two mines and has exactly two covered neighbors, both neighbors are mines. Flagging them may immediately satisfy several adjacent clues.
Subset comparison
If one clue says A and B contain one mine, while a neighboring clue says A, B, and C also contain one mine, C must be safe. If the larger group needs two mines instead, C must be a mine.
This relationship explains many patterns that do not have a memorable number name.
Pattern safety rules
- Confirm that no clue has an extra covered neighbor outside the diagram.
- Subtract existing flags before interpreting the remaining numbers.
- Do not use a memorized shape when the frontier bends around a corner.
- Verify flags independently before opening several squares at once.
- Return to the two basic deductions whenever a pattern feels uncertain.