The rules in one breath
You reveal squares on a grid that hides a fixed number of mines. Every number tells you how many of its eight surrounding squares contain a mine. Flag the mines, reveal every safe square, and the board is yours. Touch a mine and the game ends instantly — there is no partial credit.
| Difficulty | Grid | Mines |
|---|---|---|
| Easy | 9 × 9 | 10 |
| Medium | 12 × 12 | 20 |
| Hard | 16 × 16 | 40 |
On Deckmio the first click is always safe: the mines are placed after your first tap, and never on the square you opened. You can never lose on the first move — so open somewhere and start reading.
How the numbers work
A square numbered 3 has exactly three mines among its eight neighbours — no more, no fewer. That single constraint is the engine of the whole game. When a numbered square touches exactly one hidden square, and its number matches the flags already around it, every remaining hidden neighbour is provably safe.
- A 1 touching one covered square and no flags: that covered square is a mine. Flag it.
- A 3 with all three of its mines already flagged: the rest of its neighbours are safe. Open them.
- Empty squares auto-open their surroundings — one tap can cascade a whole clear region across the board.
- The mine counter shows how many mines remain unflagged. It is a cross-check, not a hint: wrong flags will silently mislead you later.
Flagging with purpose
Flags are a memory device, not a move. On the site you long-press (mobile) or right-click (desktop) to place one. Flag a square only when the logic proves it — a wrong flag is worse than no flag, because future deductions will treat it as a fact. An unproven suspicion is better left unflagged; the number rows around it will confirm or clear it soon enough.
The two deductions that solve most boards
Advanced Minesweeper has famous patterns with names, but almost all of them are combinations of two habits.
- The subtraction habit. If a number is reduced by the flags around it, treat it as a smaller number. A 2 with one flagged neighbour becomes a 1 — and now you can apply the one-hidden-square rule to it. Recount every number every turn.
- The shared-square habit. When two numbers share hidden neighbours, compare their requirements. If a 1 and a 2 both touch the same two covered squares and the 1 has no other candidates, one of those two is its mine — which means the 2’s other neighbours are safe. These pairings are where the real clearing happens.
Corners, edges and the endgame
Corner squares have only three neighbours and edge squares five, so numbers there are far more decisive than numbers in the open middle — a corner 1 is a guaranteed mine. That is why careful players open from the edges early: the strongest deductions live where the fewest squares touch. And near the end, count globally. With three unflagged mines left and only a handful of covered squares, the whole remaining board often resolves from arithmetic alone.
Sometimes the board genuinely offers no proof, and a guess is required — that is part of the game. What separates good players is how rarely they need one: every careful deduction earlier in the board shrinks the region where luck gets a vote. Put it to work on Minesweeper, then try a deduction puzzle with no luck at all in Sudoku rules or the picture-logic cousin Nonogram basics. The full catalogue is in the puzzle games guide.
