Normal sudoku rules apply. Along thermometers, digits must increase from the bulb. The marked square on the central thermo is "broken", meaning the thermo functions without that digit, but not with it. The broken cell may repeat a digit from elsewhere on the thermo. The center squares of the upper and lower 3x3 boxes contain all of the digits in the coloured squares of the central 3x3 box. The digit in the broken square of the central thermo is equal to the highest digit of exactly one of the other six thermos.