Normal sudoku rules apply. The grid is partially covered in fog; placing a correct digit may clear fog somewhere in the grid. Each of the following constraint types may contain no repeated digits anywhere in the puzzle. E.g., if a renban line contains a 5, then no other renban line cell in the puzzle may contain a 5: 1) Little Killer: Black numbers with an arrow outside the grid give the the sum of the digits on the indicated diagonal; 2) X-Sums: Red numbers outside the grid indicate the sum of the first X digits in that row or column, where X is the first digit in that row or column; 3) Digits on a purple Renban (RB) line form a non-repeating set of consecutive digits NB All Renban lines are exactly three cells long; 4) Neighbouring digits on a green German Whisper (GW) line must have a difference of at least 5; 5) The 3x3 box borders divide blue Region Sum (RS) lines into segments. Each segment along a line has the same sum.