It started with a game of sudoku in a waiting room. A hard grid, almost finished, that rare moment when nothing else exists. Then a thirty-second full-screen ad, sound blasting, impossible to close, for a game we would never install. And another one, three digits later.
The calm was being sold by the slice.
That day, we went looking for a sudoku app that respected its players and, on top of that, let you play with friends. We could not find one. The big apps live off advertising or monthly subscriptions, and every single one is solo. So we built the app we wanted. Here is what it promises.
1. Your attention is not for sale
Sudoku is time for yourself. Ten minutes of mental silence in a noisy day. Free apps live off the opposite: every interruption is their revenue, and the more the ad annoys you, the more it pays.
SudoKoum contains no advertising. Not in the free version, not in the full version, not "for now". Never. This page exists so that promise cannot be quietly walked back.
2. You buy a game once
We grew up with games you bought and owned. A monthly subscription for placing digits in boxes is a no.
SudoKoum costs €3.99, once. You try it for free, and if you enjoy it, a single purchase unlocks everything for the lifetime of your account. Cheaper than a deck of cards, with nothing else to pay, ever.
3. Sudoku is better with other people
Sudoku has a reputation as a solitary game. We know that is wrong, because we saw the opposite with our own eyes. At every family gathering, our relatives would print the same grid several times over to play against each other, pens in hand, a kitchen timer in the middle of the table. The ritual was perfect. The tooling was not: lost sheets, disputed times, and always someone suspecting the winner of having peeked at the solution.
They deserved better than the printer. Watching them play is what made us want to build SudoKoum for them. A challenge sent as a link, the same grid for everyone, each player plays whenever they want, and the leaderboard does the rest. No scheduling, no pressure, just the pleasure of measuring up against the people you love, family and friends alike.
4. Winning has to mean something
A leaderboard only has value if nobody can game it. In SudoKoum, mistakes count, hints cost points, and the score is computed the same way for everyone.
It is more demanding, and that is the point. When you beat your sister by one point on an Expert grid, that point is real.
Who makes SudoKoum
SudoKoum is made by Kaizen Suru, an independent studio. No investors demanding "aggressive monetization", no growth team, no dark patterns. Decisions get made by playing the game, not by staring at retention curves.
The app is translated into 13 languages, works offline in solo mode, and your progress follows your account from one phone to the next. The kind of details that take time to build and are only noticed when they are missing.
Our commitments, in plain words:
- Zero advertising, forever.
- A single €3.99 purchase, for life. No subscription.
- Your data is never sold.
- An honest score that cannot be cheated.
SudoKoum is coming to the App Store and Google Play. Leave your email to be notified at launch, or see how SudoKoum compares to the other apps.
Page updated on July 2, 2026. Questions? The FAQ covers the most common ones.