1. Tap any square to reveal a number — it counts mines in the 8 neighbours.
2. Use those numbers to deduce safe squares. 2 means 2 mines touch this square.
3. Long-press (or right-click) to flag a suspected mine.
4. Reveal every safe square to win. Hit a mine — game over.

Pure logic + a bit of nerve. Faster you clear, higher you climb.