Normal sudoku rules apply. All 5's in the grid must strictly have EITHER; a '1' directly above it AND/OR a '9' directly below it. The digits along each arrow must sum to the digit in the circled cell. Digits may repeat along an arrow if permitted by other rules. Adjacent digits along each German whisper line must have a difference of at least 5. Digits along each thermometer must increase starting from the bulb end. The grid is partially covered with fog. Correctly placed digits will clear the fog around that cell.