What makes it different

Hints that teach

A hint comes in three steps: where to look, which technique, then the whole step, with the cells marked on the board and a sentence that says why it holds. Twenty-seven techniques, from Hidden Single to X-Wing, Swordfish, XY-Wing and the chains.
Only the steps you need

Each hint leads to the next digit, with only the steps the solution needs, each one right before the digit it is for. Rather see the techniques in their order? That is a setting.
Lessons with real exercises

The rules, then one chapter per technique, simplest first: explained on a real position, then exercises where you find the answers yourself, and a full puzzle at the end of each chapter.
Your paper puzzles too

Stuck on a puzzle from a magazine? Take a photo or a screenshot. It is read on your device, never uploaded: check the digits, then get hints for that very puzzle.
A daily puzzle for every level

Very easy to Extreme, rated by the techniques they need, each with exactly one solution. Every day, five daily puzzles, the same for everyone: solve all five for the day's trophy.
Nothing in your way

No ads, no lives, no mistake limit, nothing to unlock, no account, no tracking. Light and dark themes, screen reader support, in five languages.