Normal sudoku rules apply. The grid is covered in fog. Placing a correct digit in a cell lifts fog in that cell and possibly other cells. The vertical dashed lines are folded onto each other so that columns 1, 2, 8 and 9 form a secondary grid (as if the other columns disappear). In this grid all clues are still valid. Digits in a cage don't repeat and sum to the total given in the top-left corner. Cages don't overlap. Digits separated by a white dot are consecutive. Not all dots are given. Clues outside the grid give the sum of all cells that contain a digit equal to the distance of that cell from that clue in the row or column. For example, a 4 in Row 2, Column 4 would count towards the 10 clue in row 2, and any other number would not. Horizontal distances in the folded 4x9 grid are limited to 1-4.