Thermo Sudoku

Thermo Sudoku

by Cracking the Cryptic

145 ratings
56 reviews
$4.99

Details

  • Released
  • Updated
  • May 20, 2020
  • April 1, 2022

Features

Thermo Sudoku screenshot #1 for iPhone
Thermo Sudoku screenshot #2 for iPhone
Thermo Sudoku screenshot #3 for iPhone
iphone
ipad
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About

This app offers a unique twist on classic Sudoku with the addition of thermometer shapes. Digits must increase along the thermometer, creating new logical challenges and patterns. Enjoy 100 expertly crafted puzzles with hints from renowned Sudoku experts.

100 unique puzzles
Thermometer logic
Expert-crafted hints
Progressive difficulty
Star-based progression
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What users say

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What's New in Thermo Sudoku

1.4

April 1, 2022

20 new puzzles, 100 puzzles total!

Charts

Top Paid

📉 177-5

Board games

This game dropped -5 positions in Board games chart.

Last updated on July 28, 2026.

User reviews

Nice Sudoku app (with one small flaw)

While the app comes with “only” 100 Sudokus, all of them are very well made. Even the easy ones take a few minutes to solve and the hard ones may even keep you busy for an hour or more. I found the puzzles to be challenging but fair. My only complaint is, that with the latest app version running on iOS 17.2 the time tracking seems to be somewhat broken, sometimes adding hours to the recorded solve time. When locking the phone while a puzzle is open, chances are, that a few extra minutes will be added to the timer _after_ unlocking the phone (you can see the timer change in one big step). The difference is also much bigger than the time the phone was locked and can quickly add tens or hundreds of hours within a a few minutes. It seems to be somewhat dependent on the pre-lock value and not really linked to the lock time; the bigger the time the more time gets added. The highest change I observed was 980 added hours within a 5 second screen lock. Which is also why the app tells me, that it took me just over 40000 hours (4.5 years) to solve level #100, which was released less than two years ago…
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Timer glitch

On iPhone, whenever playing a level on the screen if I bring down my notifications sliding down from the notch and then back up to return to the game, a 44 seconds gets added to the clock on the level; 100% of the time, same 44 seconds extra. Other than that great game.

Awful controls

The controls are so bad as to make it almost unplayable. Why not use the same number pad as Cracking the Crypto? If you fix this, i’ll change my rating to five stars.

Brilliant

Rich in customizable features and lovely, handcrafted puzzles :) Thanks for your efforts in creating these lovely apps, and the YouTube channel.

Bug: Timing Error

Great app, but sometimes when exiting and re-entering the app while solving the puzzle, the timer jumps, sometimes hundred of minutes at a time. I didn’t have this error on the Classic or Chess sudoku app.

Developer apps

User experience

🐞

Reported Bugs

11 issues

Timer adds incorrect hours/minutes

Bug

Timer adds 44 seconds when notifications are pulled down

Bug

Timer jumps when exiting/re-entering app

Bug

Wrong number put into box when leaving and loading app

Bug

Clues do not stand up to logic

Bug

Controls are bad

Bug

Erase function does not work as expected

Bug

Keyboard navigation incomplete

Bug

Arrow keys often don't register

Bug

Puzzle 24 impossible without cheating

Bug

Multiple solutions found in puzzles

Bug

Requested Features

14 requests

Fix timer glitch

Feature

Improve controls

Feature

Ensure logical clues

Feature

Add more puzzles

Feature

Unlock all puzzles

Feature

Improve hint clarity

Feature

Add synchronization across devices

Feature

Improve keyboard navigation

Feature

Add split view mode

Feature

Revert to old menu design

Feature

Allow reading hints while viewing board

Feature

Grey out used numbers

Feature

Improve erase function

Feature

Offer a theme similar to Chess Sudoku

Feature

FAQ

What is Thermo Sudoku?

Thermo Sudoku is a variation of the classic Sudoku puzzle. It introduces thermometer shapes within the grid. Digits placed on these thermometers must strictly increase as you move away from the bulb end, adding a new layer of logic to the solving experience.

How does the thermometer mechanic work?

On a thermometer, the digit closest to the bulb is the smallest, and each subsequent digit further away must be larger. This rule interacts with standard Sudoku rules to create unique logical pathways and patterns for solvers to discover.

Are the puzzles difficult?

The puzzles are carefully calibrated to offer a range of difficulties, from easy to extreme. The goal is to provide engaging challenges for solvers of all skill levels, helping them improve their Sudoku abilities.

Who created the puzzles and hints?

The puzzles and hints were personally crafted by Simon Anthony and Mark Goodliffe, the hosts of the popular YouTube channel Cracking The Cryptic. They are experienced Sudoku players who have represented the UK at the World Sudoku Championship.

How do I progress in the game?

Players start with zero stars and earn them by solving puzzles. The more puzzles you solve, the more stars you accumulate, which in turn unlocks more puzzles to play. This system rewards dedicated and skilled solvers.