Author: Andrey Bogdanov
Place a mine into some of the empty cells so that each number represents the total count of mines in neighboring cells, including diagonally adjacent cells.
Grid control: Click the mouse button at the selected cell to set/remove a mine. Second click will put auxiliary cross sign, which doesn't affect correctness of the solution, but helps visually. You can also drag the content of one cell to another with the mouse. More details about grid control are at the help page.