Thermo Sudoku

Thermo is a highly engaging variant. The board contains thermometer-shaped lines that begin with a bulb (circle shape). Thermo rules below the image.

Thermo Rules: Digits along a thermo line must be in ascending order, with the lowest digit on the bulb and the largest at the end of the line.

When two or more Thermo lines are connected, the digits are in ascending order from each bulb to the end of each Thermo line. In the image above, Thermo line with red X next to it presents illegal digit sequences, while a line with green V shows a legal digit sequence.

Thermo Tips

1. It often helps to ‘pencil mark’ the optional digits in some of the cells on a thermo line.
2. The digit 1 can be a cell solution only on the bulb of a thermo line.
3. The digit 9 can be a cell solution only in the last cell of a thermo line.