Sudoku for iPhone and iPad
Sudoku that teaches you sudoku.
Every puzzle can be solved without guessing. When you are stuck, the app shows you the pattern you missed, by name, so you find it yourself next time.
No ads. No tracking. No account.
A real position, solvable without guessing.
Hints
The three stages
Each hint goes one stage further: first the region, then the cell, last the digit. Each stage costs something in the result, and only the deepest one you needed is counted.
Where to look
The app names the row, column or box where something is due. Finding it is still yours.
−3 % on the resultWhich cell it is
The cell is marked and the text names the technique, along with any assumption still open.
−8 % on the resultWhich digit it is
Only now does the number appear. For an intermediate step it crosses notes out instead of filling anything in.
−15 % on the resultTutorial
20 lessons that show the technique.
Each lesson shows its pattern on a board where it is actually due: no single left open, no cheaper technique available. You step through it, with counterexamples for the places where people fool themselves.
Honest difficulty
Hard means logically hard. Not unfair.
The level is set by the hardest technique a board actually requires. The number of gaps does not decide it.
Screens
Screens from the app
The board No ads, no flashing, no timer pressure. 
The hint Names the technique and marks the pattern. 
Tutorial 20 lessons to step through. 
A lesson A sequence of steps, not a still image. 
Daily Challenge The same board worldwide, every day. 
Statistics Which technique sticks, and which does not yet.
Every day
One puzzle. One solution. Every day.
The daily challenge is the puzzle that counts today, the same one worldwide, generated from the date. Solve it and your streak grows. The app does not remind you that it could break.
The challenge is always free, Plus or not.
Calm as a feature
Your battery barely notices you are playing.
True black on the OLED display, not a single timer object, no continuous animation, no network access during play. The clock runs without ticking.
Streak, level and best times are on all your devices through iCloud. No account, no sign-in. Siri answers "What is my streak?" without opening the app.
Subscription
Sudoku Still Plus
Easy, Medium and the daily challenge belong to the app, along with all 20 lessons, the staged hints, the statistics and iCloud sync. Plus opens "Hard" and "Expert" in free play: boards where the patterns from the tutorial are actually needed, as often as you like. Family Sharing makes one subscription count for everyone in your family.
Help
Common questions
Do I ever have to guess?
No, on no level. Every board has provably exactly one solution, and every position can be solved with a technique the tutorial explains. If you are stuck, you are missing a pattern, not luck.
Why does the app not pre-fill notes on easy boards?
Because pre-filling there would take away exactly the work the puzzle consists of. On boards solvable with singles it is off. On hard boards you can ask for it.
Do mistakes cost me the game?
No, there is no game over. A mistake costs 8 %, a hint 3, 8 or 15 % depending on the stage, and the two together are capped at 60 %. Mistakes also melt the time bonus, which is why guessing your way through quickly gains nothing.
How does the app know which technique I can do?
After every move it asks which technique forced that move, not what it would have suggested. A paid hint does not count as found yourself. Statistics show one state per technique: new, building or solid.
Does it run on iPad?
Yes, iPhone and iPad. The layout works from the space it has, not from the device. That holds in a freely resized window too.
How do I cancel Sudoku Still Plus?
In iOS Settings, at the top under your name, then Subscriptions. Easy, Medium and the daily challenge stay open afterwards.
Contact
Questions, bugs or requests? Write to me, I reply personally.