BRIDGE NUMBER PUZZLES FOR ADULTS
One flip.
Two sums.
It all adds up.
A quiet number puzzle with a clever catch: fixing one island changes its neighbour. Can you make every sum agree?
Try your first flipSix free browser boards · No timer or sign-up
Start with one bridge.
Work up to two tides.
BOARD 1 / 6
PLAYABLE SAMPLERThe first flip
0 movesTap a bridge to swap its two numbers.
Make each island total equal its goal.
Match both islands
Swap the two numbers on the bridge to match both goals.
0 of 6 explored & solved
THE IDEA, IN ONE MOVE
You’re moving value.
Not adding more.
If a bridge gives 1 to island A and 4 to island B, a flip gives 4 to A and 1 to B. A gains 3. B loses 3. The total stays 5.
That’s the useful trick: look at what both ends need. A move that fixes one island can disturb another.
THREE THINGS TO NOTICE
Small numbers.
Real decisions.
- 01
Start at the edges.
An island with one bridge has fewer possibilities. Match that target, then follow the consequence to its neighbour.
- 02
Compare the difference.
A bridge marked 2 and 6 changes each endpoint by 4 when flipped. Does an island need exactly that change?
- 03
Check both tides.
On board five, the numbers change with the tide. Your bridge arrangement stays the same. It must work in both views.
ON IPHONE & IPAD
Keep the harbour
in your pocket.
Enjoyed the moment everything matched? Sumbriska turns bridge puzzles into a harbour you build, one solved board at a time.
- A Daily board and The Deep for another puzzle when you want one.
- Hints, Undo and explanations without an XP penalty.
- Offline play, with no ads or account.
Free download · Optional in-app subscription · iOS 18+
App details checked against the official listing on November 4, 2026. These six original web boards are a companion, not a recording of the app. Progress here does not transfer.
A USEFUL FREE START
Play first. Choose more later.
Included free
Regions 1–2, the Daily board, The Deep and Harbor Run.
Optional Voyage Pass
Regions 3–6, all side boards, Gale Run, the 3–4 ring workshop and premium cosmetics.
Auto-renewing subscription. No free trial. Check the App Store for current local prices.
BEFORE YOUR NEXT FLIP
A few good questions.
Are these number puzzles for adults?
Anyone who enjoys a quiet arithmetic puzzle can try this sampler. It starts gently and adds connected decisions. You only need addition, comparison and a little patience.
Is this the same as Hashi or a bridges puzzle?
Traditional Hashi asks you to place bridges between islands. Here, bridges already exist: you flip the numbers at their ends to match island sums. The shared island theme does not make the rules identical.
Do I have to download anything to play?
No. All six practice boards work here in a modern browser with JavaScript enabled. The separate Sumbriska iPhone and iPad app is available through the App Store.
Does the sampler save or track me?
The sampler keeps its progress in this open page only. Refreshing clears it. This page has no added analytics, ads, accounts or forms. The website host may process routine connection logs.
Is a hint a penalty?
No. Try a hint, use Undo or select any board. This sampler has no score, clock or penalty for exploring.
Another small puzzle break
- Bad at mental math as an adult: twelve answersBad at mental math as an adult? Twelve questions people ask, answered plainly, plus a calculator that shows the make-ten trick on any sum you type.
- Bridge-Sum Puzzle Maker: Create and Share an Island ChallengeChoose four island targets, test every bridge orientation and share your own playable number puzzle. Recipients get a fresh unsolved board.
- Try a three-round Sumbriska practice planA six-check practice sheet for learning Sumbriska's bridge sums without rushing: predict one flip, inspect both islands, then explain a correction.
Try a one-swap puzzle
Repair two row totals by swapping a single pair of numbers. Play five original rounds and check each result.