Thermo Sudoku

Thermo Sudoku: 200 original verified puzzles, clear candidate notes, undo and explained logical hints.

Focus
Thermo Sudoku gameplay preview

Progress stays in this browser. Export in the game before clearing browser data.

About Thermo Sudoku

Thermo Sudoku adds ordered paths. The round bulb marks the beginning; digits rise strictly toward the tip, even when the path turns. Path length and placed digits create lower and upper bounds that can be combined with ordinary units.

How to begin

Use ordinary Sudoku units. Digits increase strictly along each thermometer, starting at the round bulb. Select an empty cell before choosing a digit. Given digits stay fixed. On a keyboard, use the arrow keys to move and 1–9 to fill; on a phone, use the digit buttons below the grid.

Digits strictly increase from the filled round bulb along the drawn path. Bends do not reset the order. On a four-cell thermometer the bulb is at most 6 and the tip is at least 4.

Turn possibilities into a reason

A placed 5 at the second cell of a four-cell path forces later cells above 5 and 6. Compare those bounds with the ordinary units; a removed candidate can make another cell a single.

Two paths can influence the same row or box without touching. There is no extra anti-knight rule in this game. The direction and the current candidate sequences are what justify eliminations.

Manual notes let you record candidates without committing to a value. The optional candidate tool is an explicit action, and Undo restores the notes it replaces. A hint first points to cells worth inspecting, then explains the supported logic, and reveals a conclusion only after another request.

Choose your own route through 200 puzzles

The fixed collection is sorted using the techniques and candidate bottlenecks in its logical solutions. Puzzle selection is open from the beginning, so experienced players can choose a later puzzle and newcomers can work through the guided order. These labels describe solver evidence; they are not claims about an independently measured human completion time.

Questions while you play

Does a highlighted conflict mean the stored answer is different?

No. A conflict marks a broken rule on the current board. A digit that is different from the eventual solution may remain unmarked while it breaks no visible constraint. You can change it, use Undo or restart safely.

Is the daily selection a new puzzle?

It is a consistent daily choice from the verified collection, marked as a selection or replay. It uses a separate date-specific save and does not add to the 200-puzzle count.

Can I leave and continue later?

This browser stores each puzzle separately. Reopening restores digits, notes and undo history when the save is valid. Use the game’s Export this puzzle save control before clearing browser data; import that file into the same puzzle and mode. If browser saving fails, the game says so and keeps the current board in this tab.

Learn with the original guide: Read the bulb before the tip.

How to play

Use ordinary Sudoku units. Digits increase strictly along each thermometer, starting at the round bulb.

  1. Select an empty cell, then choose a digit or switch Notes on.
  2. Ask for a gentle hint: attention first, proof next, then the conclusion only when you request it.
  3. Undo uncertain moves or pause. Every puzzle is open; daily selections use a separate save.
Controls & saving

Select a cell · 1–9 fill · N notes · arrows move · Delete erase · Ctrl/Cmd Z undo

Automatic saves belong to this browser and this game. Changing devices or clearing browser data does not transfer them. Use the game’s save tools for an exported backup.

A gentle starting point

Digits strictly increase from the filled round bulb along the drawn path. Bends do not reset the order. On a four-cell thermometer the bulb is at most 6 and the tip is at least 4.

Read the bulb before the tip.

Another visit, your own pace

Favorite this game to find it on your Favorites page. The daily center has three dated picks each day; your game progress stays separate from them.

Today’s daily picks

More little worlds