Minesweeper

The 16×16 board with 40 mines is where minesweeper starts requiring actual technique. Mine density sits around 16%, and the board is large enough that your opening cascade won't carry you far. You need to work the frontier — the boundary between revealed and hidden cells — methodically.

This is where the 1-1 pattern earns its keep. Two adjacent 1s along a wall of hidden cells: the mine is in their shared zone, and cells touching only one of the 1s are safe. You'll see this pattern dozens of times per game. Recognizing it instantly instead of working it out from scratch each time is the difference between a fast solve and a slow one.

The 1-2 pattern shows up here too, though less frequently. A 1 next to a 2 along a wall: the 2's extra mine goes in its unique cell, the shared zone handles the 1's mine, and the 1's unique cell is safe. Getting these two patterns into your visual vocabulary handles most medium-level stalls.

Aim for consistent clean wins before moving to hard. Medium teaches you to read the frontier efficiently. Hard demands that skill constantly across a board three times this size.