A MineSweeper-style game. The object of the game is to
reveal all tiles that don't have mines hidden underneath. If you reveal a tile
that doesn't have a mine underneath, you'll find instead how many mines surround that particular tile in the minefield. If you think you know of a tile that has a mine underneath, you can hold down the control key, option key, or command key while clicking on that tile. This will plant a flag on that tile, to remind you where the mine is.
