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BGonline.org Forums
Full GNU Backgammon for Android — 3-ply, XGID paste, GPLv3, on F-Droid
Posted By: clavierhaus
Date: Wednesday, 29 July 2026, at 8:17 p.m.
Some of you may remember earlier Android backgammon apps built on gnubg's move logic. This is different: CBG (Clavierhaus BackGammon) is a full Android port of GNU Backgammon — the complete analysis engine, not just the move generator. The same neural-net evaluation you run on the desktop, on a phone, under GPLv3.
What that means in practice:
Paste an XGID or GNU BG ID from your clipboard and the engine analyses the position immediately — gnubg auto-detects which dialect it is. A position posted here goes from clipboard to full analysis on your phone in one paste, no re-entering the board.
Full match play — doubling cube, Crawford, a choice of match-equity tables including Kazaross-XG2 — at gnubg's real strength across difficulty levels, up to the World Class (2-ply) and Grandmaster (3-ply) presets running natively with pruned search.
A coach mode that flags your doubtful moves and shows the better plays with gnubg's own rank and equity, so you can step through the alternatives and see the cost of each.
Per-level statistics, including your rolls and the engine's side by side — so anyone inclined to check the dice can check them, on their own data.
Two things I think this community in particular will care about:
It's honest about what it knows. The coach shows what the engine can back — rank, equity, the candidate list. It doesn't manufacture prose explanations the evaluation can't support. Where gnubg is silent, the app is silent. I'd rather it under-claim than tell you something the engine didn't.
It's verifiable. GPLv3+, source in the open, and the F-Droid builds are reproducible — the published APK can be rebuilt byte-for-byte from source. Nothing to take on trust.
A word on where this comes from: I run clavierhaus.at, a studio in Vienna for fine grand pianos — sales and a recording studio. I'm a pianist by trade, a backgammon player, a gnubg and free software user by inclination, and the same obsession that goes into getting an instrument's voice exactly right is what went into keeping this port faithful to the engine rather than "improving" it. It's a labour of respect for gnubg, not a product.
This is where I'd genuinely value this group's input. There's a public issue tracker on GitHub:
https://github.com/clavierhaus/gnubg-android/issues
Bug reports, feature requests, and criticism from strong players are exactly what has improved it so far, and I'd rather hear the hard feedback here than anywhere else. If a position or an analysis result looks wrong to you, that is the single most useful thing you can tell me.
Free, no account, no ads, nothing network. On F-Droid now (v0.22.6):
https://f-droid.org/packages/com.clavierhaus.gnubg/
Source: https://github.com/clavierhaus/gnubg-android — with extensive documentation.
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