Frequently asked questions

Before the first roll of an online game, the server picks a secret seed — the starting value the whole sequence of rolls is derived from — and sends the app a hash of it. That hash is a commitment: the server cannot change the seed afterwards without the hash no longer matching. Every roll of that game is derived from the seed with an HMAC, so the whole sequence is fixed before you see the first die.

When the game ends, the server reveals the seed. The app hashes it, compares the result with the commitment it stored at the start, replays every roll from the seed, and checks each one against the dice you actually played. If everything matches it shows "Dice verified against the server's commitment"; if anything does not, it says the dice could not be verified. What this proves is that the rolls you were given match the sequence the server committed to before play began.

Since September 2026 the same happens offline: the app draws the seed itself before the first move. And you no longer have to trust the app's "verified" message. Open Fair dice in the pause menu at any time: it shows the commitment while the game is still running, with a Copy button. After the game the seed appears there too, and Share record exports commitment, seed and every roll as a short text. Paste that on the verification page, which recomputes everything in your browser with a script you can read; a Python script is there as well. If the hash of the seed is the commitment you copied before play and every roll replays, the dice were fixed before the first move, whatever the app says.

Settings › Dice fairness counts every die rolled on this device, yours and your opponents', and compares the observed distribution with the distribution expected from fair dice. It also shows how often doubles came up, against the expected 16.7 per cent, and the average available movement per roll, counting doubles as four moves (expected value: 8.17 pips, a pip being one step of movement on the board). That is the movement the dice offer before blocked points and other restrictions, not necessarily the distance actually moved. You can reset the counts and start a fresh sample.

The screen is a sample of your own play, not a proof on its own. For an online game, the commitment and the revealed seed described above are what let the app verify that the rolls match the sequence committed before play.

Offline there is no server, so there is nothing to commit to and nothing to reveal. The dice come from a generator seeded by the device's hardware randomness. The position, whose turn it is and the computer's level never influence a roll, and the computer sees exactly the same dice you do. Offline rolls are counted on the Dice fairness screen along with everything else.

Backgammon is a high-variance game, and streaks that feel impossible are ordinary. The chance of rolling doubles on each of three consecutive rolls is 1 in 216. Such streaks can happen to either player, but you may remember your opponent's lucky rolls more readily than your own. A particular number appears on at least one of the two dice in 11 of the 36 combinations, so it will not appear on about two out of three rolls — that counts the number showing on a die, not every way of making a move with the total.

That is also why the review exists. Over a single game, luck dominates the result and your Performance Rating swings wildly; over a few hundred decisions, it becomes more representative of how you play. The Dice fairness screen is there so the question can be settled with a count rather than a memory.

Ranked games feed a Glicko-2 rating. 1500 is the starting rating assigned to new accounts, the value given before anything is known about how you play; it is a starting assumption, not a judgement. From there the rating moves with your results against the ratings of the people you played.

Glicko-2 keeps a second number next to your rating called the rating deviation: a measure of the uncertainty in your estimated rating. A new account has a large deviation, so each result is allowed to move the rating a long way. As you play, the deviation shrinks and the same result moves the rating less.

The deviation grows again if you stop playing for a while, which is why the first game back can move your rating more than you expect.

Your rating counts as provisional until you have three ranked results. Until then it is shown in the app but kept off the ladder, because a table built from single games would be mostly noise. Play three ranked games and the row appears.

Yes. A game is scored as money play, so the points it is worth are the value of the doubling cube multiplied by one for a plain win, two for a gammon and three for a backgammon. Those points weight the rating update: a doubled gammon moves both ratings further than an undoubled single game, and the weighting is capped at 8 points. It also means a game you should have declined the cube on can cost more rating than the win was worth.

Standard Glicko-2 works from win, loss or draw alone. Weighting the update by the points of the game is this app's own adaptation of it, which is why the ladder is described as Glicko-2 with score weighting.

The season is a separate monthly total of points won and lost in ranked games, kept next to the rating. Every ranked game transfers its points from the losing player to the winner, so the table is a record of what was won from other players this month. Points are earned only. There is no way to buy them and no way to top them up.

The table resets at the start of each month so a new player can reach the top of it without a year of catching up, and your lifetime total is kept separately.

Three online games a day are free, and one of those three may be ranked. Club members play as many online and ranked games as they like. The daily allowance is counted per device, and it resets every day.

Your handle is a display name you choose plus a numeric tag the server gives you. Display names are not unique — several people can call themselves Robin — and the tag is what tells them apart. Friend requests and invites use the whole handle, name and tag together, so type both when you add someone.

You can change the display name under Account at any time; the tag stays with the account.

Before you roll, you may offer to double the points at stake in the game. Your opponent then takes or passes. If they take, the game continues for twice the points and the cube moves to their side, so only they may double next. If they pass, the game ends immediately and you win the points the cube was worth before the offer.

Because a pass hands over a small certain loss and a take risks a larger one, cube decisions can have a large effect on the expected value of a position. The cube can be switched off in Settings if you would rather play without it.

The rough baseline is that you can take while you still win about one game in four from the position. That 25 per cent figure assumes a plain win or loss with no gammons, and it ignores cube ownership and any redouble later in the game; gammon and backgammon risk pushes the threshold up, while owning the cube afterwards pulls it down. It is a starting point, not a universal threshold. The engine's answer is more exact than a rule of thumb, and the review grades your take and pass decisions the same way it grades a chequer play, with the equity you gave away.

The engine evaluates cube decisions taking the doubling cube into account (cubeful), using the live-cube model: it weighs the expected value of the position with the cube where it would end up, including the option of doubling later, rather than reading a win probability off a static board. A position that looks close on wins alone can be a clear double once the gammons and the future ownership of the cube are counted.

If you disagree with a decision it made, the review after the game shows the equity of both choices.

Yes. Undo takes back the part of your turn you have played while the turn is still open. With "Confirm my turn" switched on in Settings, your turn stays open until you tap Done, so nothing is committed while you are still moving chequers around. With it off, the turn is confirmed automatically once you have played all the moves for that turn. A turn in which you had no choice ends by itself either way.

PR is the Performance Rating: it summarises the average equity lost per counted decision, multiplied by 500. Equity is the expected value of a position, measured in points per game, so a play that loses 0.02 equity is a small error and one that loses 0.4 is a serious one. Each graded turn of chequer play and each cube decision counts as one decision.

Lower is better. The result depends on the analysis engine, the analysis settings and which decisions are counted, so a PR from this app may differ from a score reported by another app for the same game.

The app labels a PR under 2 as world class, under 4 as expert, under 6 as advanced, under 8 as intermediate, and under 12 as casual; 12 or higher it calls beginner. These are the app's guide categories, not universal standards.

Read a single game's PR with care. One blunder in a six-turn game produces a huge number, and one lucky game produces a flattering one. The figure becomes more representative over many decisions. A PR of zero means no errors were measured against the engine's own evaluation, not proof of objectively perfect play.

Without the Club, the review opens the three turns where you lost the most equity, largest first, which is where nearly all of the lesson is. A turn is all the chequer moves played from one roll; a cube decision counts as a turn of its own. Club members can open every graded turn of the game. The Performance Rating for the game is shown either way.

Yes. "Share match file" exports the game as a .mat file, the standard match format, which you can send on or open in XG or GNU Backgammon for further analysis. The file contains the moves and the dice of the game, the result and the names of both players as the app shows them, which for an online game includes your opponent's display name. Nothing else about your account is in it.

Unlimited online and ranked play instead of three games a day, the full post-game review instead of the three largest errors, your full match history instead of your recent games alone, and cloud save for an unfinished offline game. It does not change the engine, the dice or the ratings, and there is nothing purchasable anywhere in the app that affects the outcome of a game.

€9.99 a year, starting with a free 7-day trial, or €19.99 once for life. Prices are quoted in euro; your store shows and charges the equivalent in your own currency. Offline play stays free either way, and so do three online games a day, one of them ranked.

The subscription is billed by Apple or Google, not by Knipsoft, so it is cancelled in your store account: on iPhone, iPad or Mac under your Apple Account subscriptions, and on Android under Payments and subscriptions in the Play Store. Cancelling during the trial costs nothing. Membership runs to the end of the period you have paid for. The lifetime unlock is a one-off purchase that does not renew, so there is no recurring subscription to cancel; refunds for it are handled by the store you bought it from, under that store's policy.

Tap "Restore purchases" in the Club screen; the app asks the store again and activates the membership when the store confirms it. It can take about a minute for a purchase to show up in the app, so if the app says the purchase went through but the membership is not active yet, wait a moment and tap "Restore purchases" again. Make sure you are signed in to the store account that made the purchase, and if it still does not appear, write to support@knipsoft.com.

Membership follows your account, and the account follows a Sign in with Apple or Google sign-in. Sign in with the same Apple or Google account on each device and the same membership, rating, friends and season points are there. Without linking a sign-in provider, you can access this account only from the device where it was created. Losing the device or deleting the app's data can mean losing access to the account, and to the membership with it.

Apple and Google are separate stores, so a purchase made on one is not automatically a purchase on the other; buying on Android and then signing in with Google on a second Android device works, and so does buying on iPhone and signing in with Apple on a Mac.

Add them by their full handle, the display name and the numeric tag together, for example Robin#4821. They receive a request and the two of you become friends when they accept. Your own handle is shown at the top of the Friends screen so you can read it out or send it on.

An invite reaches a friend only while they are online in the app; the friends list shows who is. There are no push invitations to a closed app, so arrange a time to play, or use a private room and send the code instead.

One of you opens a private room and gets a four-letter code. The other types that code and the two of you are put into the same game, without going through matchmaking. It works with people who are not on your friends list, since anyone who has the code can join. Private games are not ranked.

Easy, Normal and Hard. Hard is the full-strength engine, the one measured at PR 0.7. Normal is the same network judging every legal play one move ahead, and Easy is weaker again. The dice are the same for the computer as for you at every level; the levels change how well it plays, never what it rolls.

Hint plays out the engine's answer for the position in front of you, and Undo takes back what you have moved while your turn is still open. Beginner help numbers the points from your side of the board, highlights the legal chequer moves for each die, and tells you why a move you tried is not allowed. Use these tools whenever you need them.

Yes. Pass and play hands the board to the person sitting opposite between turns, on one phone, tablet or Mac. It is a single game with the doubling cube, scored as money play: the points are the value of the cube multiplied by one for a plain win, two for a gammon and three for a backgammon. No account and no connection are needed.

Not to play. Offline play needs nothing at all and sends nothing to us. The app creates an account the first time you use an online feature, not when you first open it: a guest account, created without a name or e-mail address, consisting of a random identifier and a secret kept on the device. Signing in with Apple or Google is optional, and its only purpose is to let the same account follow you to another device. Without linking a sign-in provider, you can access this account only from the device where it was created.

Your account identifier, your display name and numeric tag, a random device identifier used for the daily free-game allowance, your online match history (opponent, result, points and rating change), your rating, your season points and your friends list. Club members also have a cloud save of one unfinished offline game. If you sign in with Apple or Google, the provider's user identifier is stored so the account can be found again.

There is no advertising in the app, and no advertising or usage-analytics SDKs. We do not sell your personal data, and we do not share it with third parties for their own purposes; processing by our service providers is described in the privacy policy.

Account › Delete account, in the app. It removes the account and the personal data attached to it, including the display name, the friends list, the rating and the season entries. Rows in other players' match histories keep the result of the game without the deleted account's identity, so their own history and rating stay correct.

Deleting the account does not cancel a subscription, because the subscription is held by Apple or Google — cancel that in your store account.