Box Brain Sudoku
Rules › Thermo
How to play Thermo sudoku
Thermo sudoku adds thermometers to the grid. Each one tells you the order of the digits along it, which often fixes digits with very few givens.
Digits that climb.
The rules
- Classic rules apply: every row, column and 3×3 box holds the digits 1 to 9 once each.
- Along each thermometer, digits get bigger from the round bulb to the tip.
Where to start
- A long thermometer squeezes its digits: a 9-cell one must read 1 to 9 in order.
- A cell n steps from the bulb is at least n + 1, and a cell n steps from the tip is at most 9 − n.
- Digits never repeat on one thermometer, because each must be bigger than the last.
Play Thermo in Box Brain Sudoku
Every Thermo puzzle in the app has exactly one solution and can be solved by logic alone, from Easy to Expert. Stuck? A hint first nudges you towards the right area, then names the technique and shows the move.