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.
A common strategy for starting games is to randomly click until you get a big opening with lots of numbers. If you flag all of the mines touching a number, chording on the number opens the remaining squares. Chording is when you press both mouse buttons at the same time. This can save you a lot of work!