Clack
Old game. Exact odds.
Shut the Box for iPhone and iPad, solved exactly — so it can tell you what every cover is worth, the moment you choose it.
£3.99, once · iOS 26.0 or later · no ads, no in-app purchases, no account
Play a box
Practice · 9 tiles · one-die rule
Roll to start
Roll the dice, then tap tiles that add up to the roll.
9.76% to shut
A real nine-tile box with Coach on. The odds come from the app’s own solver, running in this page.
What Coach tells you
Shut the Box looks like luck, and mostly it is. But every roll you can cover more than one way is a decision, and some of them are worth far more than they look.
Take 1 2 3 6 9 up and a 9 to cover. Three covers fit. Covering the 9 leaves a 24.15% chance of shutting the box; 6 + 3 leaves 8.46%, and 6 + 2 + 1 leaves 5.25%.
The reason is what each one leaves you to roll at. After the 9, the 1 2 3 6 still up can cover any total two dice can show. After 6 + 3, the 1 2 9 left cannot cover 4 to 8 — 63.89% of rolls.
Coach shows this as you play, under the tiles: what your hand leaves and, when it is not the best, what the best cover would — without naming it, so the thinking stays yours. Turn it off for a plain game; every figure is still there in the review afterwards.
Practice · 9 tiles · one-die rule
Rolled 9
6 + 3 leaves 8.46% to shut
Best cover leaves 24.15%
| Cover | Chance to shut the box afterwards |
|---|---|
| 9 · best | 24.15% |
| 6 + 3 | 8.46% |
| 6 + 2 + 1 | 5.25% |
Exact, not estimated
9.76%
The chance of shutting a fresh nine-tile box, playing perfectly with the single-die rule: about 1 in 10.
0.47%
The same for twelve tiles: 1 in 211, even with every call right.
190 of 1,774
Decisions in the nine-tile box, single-die rule on, where “take the biggest tiles” is the wrong call.
Every one of them is worked out, position by position, by the solver inside the app. The maths of Shut the Box has the rest, and a calculator for any roll.
The daily box
One box a day, the same for everyone. A new one opens at midnight UTC, with the same dice for every player in the world. You get three attempts, and every attempt rolls the same dice in the same order — so the second try is where you stop playing the odds and start playing the dice.
Your best score goes on the day’s Game Center leaderboard. The daily is always the classic nine-tile box with the single-die rule, and Coach sits it out, so the leaderboard stays fair. Once the day is done, Clack shows what was possible: the best score today’s dice allowed — whether the box could have been shut at all — and the line of play that gets there.
Pass and play
Two to four players, one phone or iPad passed round. Each player gets a box and dice of their own. Shut the box and you win outright — the game ends there. Otherwise the lowest score wins, and a tie is shared.
Players are named, never coloured. The only colour in a turn is the name of whoever is playing.
What’s not in it
No adverts
Not on the board, not between rounds, not ever.
No in-app purchases
The price is the whole price. No coins, no unlocks, no subscription.
No account
No sign-in and no email address. The daily leaderboard is Apple’s Game Center, if you use it.
No tracking
The app collects nothing: no analytics, no identifiers, nothing sent anywhere but Game Center.
What it costs
£3.99, once — $4.99 in the US. That is the whole business model: no adverts, no in-app purchases, no subscription. Clack runs on iPhone and iPad, and once it is bought it is yours on every device signed in to your Apple Account.
Clack is not on the App Store yet. The badges on this page become links the day it is.
Old game. Exact odds.
£3.99 once, for iPhone and iPad. iOS 26.0 or later.