Chess Puzzles

Chess Puzzles is an entirely offline tactics trainer. The installer includes 9,000 puzzles from Lichess, so there is no account, daily server quota or model download before you can solve them. It also includes 20 chess openings with a Learn section followed by practice.

The app has three difficulty bands, optional hints, progress and streak tracking, including a daily streak. Pieces can be moved by touch or drag. We did not rate the hint quality or complete enough puzzles to verify the difficulty labels against a player rating.

Where the 9,000 puzzles came from

The fixed source includes a CSV with 9,001 lines: one header plus 9,000 puzzle records. Its docs/DATA.md documents the selection from the Lichess Open Database:

• puzzles needed a popularity score of at least 85 and at least 60 recorded plays;
• ratings were stratified across six bands rather than taking only the most popular easy positions;
• only puzzles carrying common tactical themes were eligible, with up to 1,500 sampled from each band;
• the resulting ratings run from roughly 400 to 3,300.

The script uses a fixed random seed, but that alone does not make the set permanently reproducible. The project notes that Lichess’s download is not versioned, so an exact rerun also needs the same database snapshot in the same record order.

Lichess publishes the puzzle database under CC0. The opening names and ECO data used by the 20 lessons also come from Lichess under CC0.

Why the first move is automatic

A Lichess puzzle begins from the position immediately before the opponent’s move that creates the tactic. Chess Puzzles therefore plays that first move for the opponent, then gives control to the user. This is expected data behaviour, not the app solving the user’s first turn.

Because the data is bundled, the set does not grow until a new APK includes a refreshed database. There is no live Lichess account sync, online game board or server analysis. Use the official Lichess app if those are the features you need.

Offline and file facts

The manifest has no internet permission. Puzzle data, opening lessons, progress and streaks remain local, although Android’s app-backup system may carry app data to a restored device depending on the user’s backup settings. Our static scan found no known tracker SDKs.

• Version 0.5.21, build 5021, is 1.8 MB and needs Android 7.0 or later. It contains native libraries for 32- and 64-bit ARM and x86 devices.
• Its SHA-256 is 155a4d4f448ed9f440151e0040f1e798eb9efd5bf292872fef522ef02cbe678f, matching F-Droid’s signed index. The signing certificate identifies developer Babak Bandpey.
• The app is Apache-2.0 licensed; its chess library is also Apache-2.0, and its bundled Lichess data is CC0.

CPU types in this build: arm64-v8a (64-bit ARM, almost every phone since 2017); armeabi-v7a (32-bit ARM, older and budget phones); x86 (32-bit Intel, emulators); x86_64 (64-bit Intel, emulators and Chromebooks).

Versions currently kept in the F-Droid repository. We host and check only the newest one. Full changelog.