Normal sudoku rules apply. Along the thermometer, digits increase from the bulb end. The 'v' between two adjacent cells indicates that the cells sum to 5. The orange lines - three horizontal and five vertical - are sequences of digits with the property that successive digits must be at least 4 more or less than the previous digit. All sequences are to be read left to right, or top to bottom, as appropriate, and no two sequences are the same. Each sequence has the property that the final digit is a 'dead end' - that is, there are no valid digits that could follow it, were the line one cell longer. So for a five-cell line, 28194 would be valid as the 4 is a dead end (only an 8 or 9 can follow a 4), but 28193 would be invalid as a 7 could follow the 3.
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