Find the empty squares while avoiding the mines. The faster you clear the board, the better your score.
Uncover a mine, and the game ends.
Uncover an empty square, and you keep playing.
Uncover a number, and it tells you how many mines lay hidden in the eight surrounding squares
If you suspect a square conceals a mine, right-click it. This puts a flag on the square.
If you're not sure, right-click again to make it a question mark.
If you play using flags, press right click on a number to open all squares surrounding. That's the fastest way to play Booom.