Free
With Ads
Rating summary
About
Happy Sudoku is a clear, easy-to-start Sudoku app.
Classic 9×9
Easy, Medium, Hard, and Expert. The selected cell, its row and column, and matching numbers are highlighted. Wrong entries count toward a mistake limit.
Diagonal
Both main diagonals must also contain 1–9 with no repeats.
Daily challenge
One fixed puzzle each day.
Notes and tools
Mark candidates, or mark digits in red to exclude them. Erase, undo, and redo. A few hints each game. Timer with pause.
Learning mode
A 4×4 board for learning the rules before the full grid.
Symbol themes
Switch from numbers to animals, fruit, or colors.
Themes and stats
Several palettes and text sizes. Local stats by difficulty. Resume an unfinished game from the home screen.
Offline. No account. Progress stays on this device. Includes banner ads.
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What's New in Sudoku Happy Day
1.1
October 21, 2026
Diagonal Sudoku, where both diagonals must also be unique. Exclude notes mark digits in red.





