Normal sudoku rules apply. Shade some cells such that all shaded cells are orthogonally connected and all unshaded cells are orthogonally connected and no 2x2 area may be fully shaded or unshaded. Digits on an arrow sum to the digit in that arrow’s circle. The digit in the arrow circle is equal to the sum of all shaded cells in the direction of the arrow tip (beginning from the next cell after the arrow tip).