Minesweeper Patterns & Strategy Cheat Sheet

Whenever you see a straight edge with 1 - 2 - 1 facing three unopened frontier tiles:

• The mines are guaranteed to be under both 1s (💣).
• The tile directly under the middle 2 is 100% safe to open (✓).

Why this works: The center 2 requires 2 mines. Each flanking 1 can only touch at most 1 mine. The only way to satisfy the center 2 without exceeding the capacity of either 1 is placing one mine on each end, leaving the center tile completely bomb-free.

When you encounter 1 - 2 - 2 - 1 along an unbroken frontier of four unopened tiles:

• The mines are directly beneath both 2s (💣).
• The tiles beneath the outer 1s are 100% safe to dig (✓).

Why this works: The outer 1s restrict their respective pairs to only 1 mine each. Since the two inner 2s together demand two mines across their shared territory, those two mines must sit squarely below the 2s, immediately clearing the outer tiles.

Along any wall or boundary, when a 1 has all its possible mine locations completely contained inside the neighborhood of an adjacent 1:

• Any remaining hidden tile touching only the second 1 is guaranteed safe!

This is known as Subset Subtraction—the mathematical foundation powering pure deductive logic.

When a 1 is anchored against a corner or dead-end wall and sits next to a 2 facing the open board:

• The corner 1 bounds its two tiles to exactly one mine.
• The 2 requires two mines total—one inside the 1's zone and one outside.
• Therefore, the third unshared tile directly facing the 2 is guaranteed to be a mine (💣).