Minefield (the grid of gray squares) contains a number of mines and a number of safe squares. Start by clicking on any square to reveal an initial group of safe squares. Each safe square contains a number which indicates how many mines are next to that square. A safe square with no number at all has no mines next to it. Using the revealed numbers, calculate which spaces are safe to click on - that is, which spaces can't possibly contain a mine - and click on them to reveal more numbers. Also, calculate which spaces contain a mine, and flag them (right-click). Don't guess unless you don't have a safe move! Avoid all the mines, and eventually every space on the board will be either revealed or flagged, and you'll have successfully cleared the minefield!