mincho.milev@gmail.com
For anything: a bug, a wrong puzzle, a question about a purchase, or a disagreement with an evaluation. Write in English or Bulgarian.
Support
Ask a person
There is no ticket system, no chatbot and no help centre with 400 articles in it. There is an email address and an issue tracker, and both reach the person who wrote the app.
Issue tracker
GitHub issues
For anything you would rather were public — and for anything you want other people to be able to find later, which is most bug reports.
If a puzzle is wrong
Send four things and it can be checked in a minute.
- The FEN shown on the puzzle screen — tap and hold to copy it.
- The move you played, and the move the app said was right.
- Which mode you were in.
- The app version, from the About screen.
Puzzles do occasionally disagree with a deeper search, and the disagreements cluster on long, quiet, highly rated positions whose point lies deeper than the verification searched. That is a limit of the check rather than a fault in the puzzle — but it is worth knowing which ones, and the only way to know is if you say.
Questions
Asked often enough to write down.
- Does it need an internet connection?
- No. The engine, the puzzles and your progress are all on the device. The single exception is online play, which needs Game Center to reach the other person.
- Is there an account?
- There is none to create. Your ratings and history live in the app’s own container on your device, and deleting the app deletes them.
- What is free?
- Playing is free and stays free — against the engine and against a person, unlimited. The free tier also gives you five puzzles, one Rush run and three each of the positional exercises, endgame drills and games to judge, every day, resetting at midnight.
- Why is there no advertising?
- Partly taste and partly licence. The app links Stockfish, which is GPLv3, and compiling a proprietary advertising SDK into the same binary would make the combined work undistributable under that licence. Selling the app is fine — the GPL has never forbidden charging — but bolting a closed SDK onto it is not.
- Are my puzzle ratings the same as a FIDE rating?
- No, and they run several hundred points higher. They measure progress against yourself, not strength against a field.
- Where do the puzzles come from?
- Most are from the Lichess puzzle database, released into the public domain under CC0, carrying ratings calibrated against millions of real solving attempts. The rest were mined locally by having Stockfish play itself and keeping only positions where one move is far better than every alternative.
- Can I see the source code?
- Yes. The app is licensed under the GNU General Public License version 3, and the complete corresponding source is published on GitHub.