Normal sudoku rules apply. The grid is covered in fog. Placing correct digits reveals clues in the surrounding 3 by 3 area. All golden lines are "nabner" lines ie they cannot contain repeated digits and no two digits along a line may be consecutive. Eg if 5 is on a line, 4,5 and 6 cannot appear anywhere else on the line. Clues outside the grid give the sum of the first X digits along that row or column (the 'X-sum'), where X is the first digit seen from the direction of the clue. In addition to any nabner lines revealed as the fog lifts, every X-sum forms a hidden nabner line at least X cells long starting from the cell closest to the clue.