Backgammon Duo, by Knipsoft
A world-class engine that reviews your play.
A neural network measured at a Performance Rating (PR) of 0.7, and a review that grades your play as soon as the game ends. No advertising, no in-game currency and no purchases that give you an advantage during play.
iPhone, iPad, Mac and Android. English, Dutch, German and Turkish. Every player sees the three largest errors of a game; the full turn-by-turn review is part of Club membership.
- PR 0.7Measured over 1000 money games against GNU Backgammon's 2-ply analysis
- 1.6 / 0.5Chequer-play and cube-decision error rates in mEMG, over the same 1000 games
- 20 millionAnalysed positions the network was trained on
- No adsNo advertising, no in-game currency and no paid gameplay advantages
The engine
Measured playing strength.
The engine is a neural network trained against GNU Backgammon on more than 20 million analysed positions. Measured over 1000 money games against GNU Backgammon's 2-ply analysis, it plays at a Performance Rating of 0.7 — chequer-play error 1.6 mEMG, cube-decision error 0.5 mEMG, where one mEMG is a thousandth of a point of equity lost per decision. A PR below 1 is engine territory; the strongest human players typically play around 2 to 4 in tournaments.
The engine bases its doubling and acceptance decisions on the expected value of the position (its equity), including the future use of the doubling cube — a cubeful evaluation, using the live-cube model — rather than on a static win probability.
GNU Backgammon is named here only as the benchmark the engine was measured against. There is no affiliation with, or endorsement by, the GNU Backgammon project, and no GNU Backgammon code or data ships in the app.
The review
See the move you should have played.
Every turn is graded — inaccuracy, mistake, blunder — and the better play is drawn on the board as arrows, so you see the move rather than read about it. A turn is all the chequer moves played from one roll; cube decisions are graded in the same way. After each game you see your Performance Rating for it: the average equity lost per graded decision, multiplied by 500.
Export the game as a .mat file to send on, or to open in XG or GNU
Backgammon. Without the Club, the review opens the three largest errors of the game;
Club members can open every graded turn.
Online play
A ladder, a season, and dice you can verify.
Casual and ranked
Matchmaking for a casual match, which leaves your rating alone, or a ranked match, which affects your rating: Glicko-2 with score weighting, the app's own adaptation in which the points of a game weight the update. Complete three ranked games to appear on the ladder.
A monthly points season
Ranked games transfer season points from the losing player to the winner. Points cannot be bought. The table resets every month; your lifetime total is kept.
Friends and private rooms
Add friends by their handle — a display name plus a numeric tag, like Robin#4821 — see who is online and invite them. Create a private room and share its four-letter code. Anyone with the code can join.
Verifiable dice rolls
Before the first roll, the server commits to a secret seed — the value every roll of the game is derived from. At the end of the game, it reveals the seed so the app can verify that every roll matches the sequence committed before play.
The Club
Unlimited play. No paid gameplay advantages.
Offline play is free, and so are three online games a day, one of them ranked. The Club lifts the online limits, opens the full review instead of only the three largest errors, keeps your full match history instead of your recent games alone, and turns on cloud save for an unfinished offline game.
Free
€0- All offline play, all three levels
- Three online games a day, one ranked
- The three largest errors of each game
Yearly
€9.99- Starts with a free 7-day trial
- Unlimited online and ranked play
- The full review, your full match history and cloud save
Lifetime
€19.99- One payment, no renewal
- Everything in the yearly plan
- Tied to your account, on your other devices too
Prices are shown in euro; your store charges in your own currency. Subscriptions are billed by Apple or Google and can be cancelled in your store account at any time.
Offline play
Three levels, and help when you want it.
Easy, Normal and Hard, where Hard is the full-strength engine. Use Hint when you need help and Undo to reconsider a move before ending your turn. Pass and play on one device when someone is sitting opposite. Single games with the doubling cube, scored as money play: the points for a game are the value of the cube multiplied by one for a plain win, two for a gammon and three for a backgammon.
Beginner help numbers the points, highlights the legal chequer moves for each die, and says why a move is not allowed. "Confirm my turn" leaves your turn open for Undo until you tap Done. The doubling cube can be switched off.
Languages and platforms
One account, four languages, four platforms.
Backgammon Duo runs on iPhone, iPad, Mac and Android, in English, Dutch, German and Turkish. On the Mac it is the same board in a window or full screen; move the chequers with a mouse or trackpad. Your account and Club membership are the same on Mac, iPhone and iPad, and cloud save carries an unfinished game between them.
Read the FAQ for the dice, the ladder, the cube and the review in detail, or write to support@knipsoft.com.