Place correct digits, shading, or loop lines into the cells to clear the fog. Contained within the grid are nine non-overlapping 3x3 square regions which must be located. Each region contains the digits 1 to 9 once each, and digits cannot repeat in any row or column. Cells outside regions do not contain digits and are considered "empty" for rules below. The digits in each cage sum to the clue in the top left corner, and may not repeat. Cages may include shaded and/or unshaded empty cells, but such cells do not contribute to the cage total. Shade some empty cells black so that no two shaded cells are orthogonally adjacent (including given shaded cells), and draw a non-intersecting loop through the centres of all unshaded empty cells. Arrow clues must contain a digit and be part of a 3x3 region; these clues represent the number of shaded cells in a straight line in the indicated direction. In the final grid, all cells will contain either a digit (with or without an arrow), a loop line, or black shading.