9X9 Primary Minesweeping
Guide
Basic Rules
Goal:
Uncover all non-mine squares without detonating any mines.
Number Meaning:
Each number indicates the count of mines in its 8 adjacent squares.
Actions:
- Left-click: Uncover a square.
- Right-click: Flag a mine (place a flag).
- Double-click / Simultaneous left + right click: Quickly clear surrounding safe squares (when all adjacent mines are correctly flagged).
Opening strategy
First-Click Techniques:
- Prefer clicking the center area of the board (e.g., row 5, column 5) because edge tiles are more likely to be surrounded by numbers, aiding later deductions.
- If the first click reveals a large blank area (a high-probability outcome), it quickly establishes a safe zone for further exploration.
Observing the "Blank Area":
- Blank areas (empty white zones without numbers) are always
bordered by numbered tiles, which serve as key starting points for subsequent logical reasoning.
Core reasoning skills
The 1-1-1 Corner Rule
If three consecutive 1s are aligned along the edge of the board, the middle cell must be a mine
The Number Subtraction Rule
When a number has been marked with some thunder,Remaining mines = Number - Marked mines
2 needs 2 mines in total.1 mine (F) is already marked → 1 more mine remains in the unopened cells.
The remaining unopened cells around 2 must contain exactly 1 mine, while the others are safe.
Cross-tabulation method
Determine the location of the mine by combining adjacent numbers.
Cell B: Must cover the 3 cells above it (including the one to the right of Cell A).
Cell A: Must place one mine in one of the 3 cells to its right.
It can be inferred that one of the two cells on the right side must contain a mine; mark it first and avoid it.
Advanced Probability Techniques
Edge priority principle:
Prioritize solving numbers on the edges or corners of the board, as they have fewer adjacent squares, making the reasoning simpler.
Mandatory probability selection:
When uncertain, choose the location with the lowest mine density in the unexplored area (such as the remaining area where many mines have already been excluded).
Avoiding the '50% Trap':
If two cells have the same probability and you must choose one, delay the decision and first handle other areas where the outcome is certain.