We mark cells with a flag to mark them as mines and so to avoid clicking on them with the left key. The game is over if we accidentally click with the left mouse key on a cell that has a mine.
The game features a grid of clickable tiles, with hidden "mines" (depicted as naval mines in the original game) scattered throughout the board. The objective is to clear the board without detonating any mines, with help from clues about the number of neighboring mines in each field.