The rules
The field hides a number of mines under covered cells. Open a cell by tapping it. If it is safe, it shows how many of its eight neighbours contain a mine; a cell with no neighbouring mines opens its whole neighbourhood automatically.
Mark cells you know to be mines with a flag: long-press, right-click, or switch the pad to flag mode. Tapping an opened number whose mines are all flagged opens the rest of its neighbours at once. You win when every safe cell is open.
No guessing, ever
Classic mine games often end with a coin toss between two cells. Here each field is generated together with a solver: starting from the opening, the solver must be able to clear the whole board by deduction, otherwise the field is rebuilt. Every numbered and daily field starts with that opening already uncovered.
In free play your first tap is always safe and always opens a patch, because the field is generated around it.
Field sizes
Easy: 9×9 with 10 mines, and every cell can be decided by looking at a single number. Medium: 16×16 with 40 mines, where you sometimes need to compare two neighbouring numbers. Hard: 30×16 with 99 mines, where the last cells may depend on the total mine count. On narrow phone screens the wide hard field turns upright so the cells stay large enough to tap.
Patterns worth knowing
A 1 touching exactly one covered cell means that cell is a mine. A number whose mines are already all flagged means every other covered neighbour is safe.
Along a straight edge, the pattern 1-2-1 means the two cells beside the 1s are mines and the one beside the 2 is safe, while 1-2-2-1 puts the mines beside the two 2s. When two numbers share most of their neighbours, subtract one from the other: the difference must lie in the cells they do not share. The mine patterns guide shows these with diagrams.
Questions
What if I open a mine by mistake?
The board shows where it was, and you can undo that move and carry on. The mistake is counted in the result.
Why are numbered fields already partly open?
Each numbered and daily field comes with the opening the solver started from, so everyone plays the same position from the first move.
How do I place a flag on a phone?
Long-press the cell, or switch the pad below the board to flag mode and tap.
Is this a copy of an older desktop game?
No. Mine-clearing puzzles are a common genre; this version is built from scratch, with its own look and the no-guess guarantee.