Intermediate Minesweeper (16×16 · 40 mines)

The Intermediate board: 16×16 with 40 mines

Intermediate has 256 squares and 40 mines, about one square in six. The open areas are smaller than on Beginner and the edges between open and closed squares are longer and more tangled, so you spend more time reading numbers and less time clicking. This is where patterns start to matter.

Every Intermediate board here is checked before you play it and can be finished with logic alone. That matters more at this level than you might think: in our tests only about 65% of plain random Intermediate boards happened to be guess-free, so roughly one random board in three hides a forced guess somewhere.

Patterns that solve most Intermediate boards

The basic rules still come first: a number that touches exactly as many closed squares as its value means all of them are mines, and a number that already has all its mines flagged means its other neighbours are safe. When neither rule applies, compare two neighbouring numbers.

Along a straight edge, a 1-1 starting at a wall tells you the third square is safe. A 1-2-1 means the squares under both 1s are mines and the square under the 2 is safe. A 1-2-2-1 means the two squares under the 2s are mines. These shapes come up constantly on Intermediate, and once you recognise them you can open whole stretches of the board without hesitating. The How to play page has a diagram of each one.

When you are stuck

Because every board is guaranteed solvable, being stuck always means there is a deduction you have not seen yet — never that the board is unfair. Look at each part of the boundary separately. Try assuming a square is a mine and follow what the numbers around it would then require; if that leads to a number with too many or too few mines, the square must be safe.

Near the end of a game, count the mines that are left. If the mine counter says two and only one arrangement of the remaining closed squares can hold exactly two mines, that decides it. The solver that checks every board uses exactly this kind of reasoning, so the answer is always there.

Playing Intermediate on a phone

A 16×16 board fits on a phone screen with squares large enough to tap. Long-press to flag, or switch on flag mode under the board. Tap a number whose flags are complete to chord. If you play often on your phone, the app (coming soon) keeps your times, streaks and daily boards in one place, without ads.

On a computer, the fastest way to play is with the mouse alone: left-click to open, right-click to flag, and left-click a finished number to chord. Flag only the mines you need for a chord — every extra flag is an extra click. When Intermediate starts to feel routine, Expert uses the same patterns on a board almost twice the size, with a higher density of mines.

Questions