Normal Sudoku rules apply: Place the digits 1-6 in each row, column, and box. Ambiguous Thermos: Digits strictly increase along the gray lines from bulb to tip. The bulbs of the lines need to be deduced by the solver. The bulb will always be on one end of the line, never in the middle. Little Killer: Numbers outside the grid are the sum of the digits pointed to along the indicated diagonal. Digits are allowed to repeat along those diagonals as normally allowed by the other rules.