Normal sudoku rules apply. Shade some cells in the grid such that all shaded cells are connected orthogonally and all unshaded cells are connected orthogonally. No 2x2 area may be fully shaded or fully unshaded. Digits in cages cannot repeat and must sum to the small clue in the top left corner of the cage. However, shaded cells are treated as negative. In other words, the cage total is the sum of unshaded cells minus the sum of shaded cells.