Bridges puzzle guide
How to solve Hashiwokakero, step by step
Hashiwokakero — also called Hashi or the bridges puzzle — has exactly one solution on every properly made board, including every one below, and a chain of deductions that reaches it. This page teaches you that chain with four real puzzles you solve right here, not screenshots.
The rule
Four sentences, and that is the entire rulebook:
- Every island shows a number — exactly how many bridge-ends must touch it.
- Bridges run only horizontally or vertically, never diagonally.
- Two islands can be joined by at most two bridges — tap once for a single bridge, again for a double, a third time to remove it.
- Bridges can never cross, and every island must end up in one single connected network — no island left out, no separate group.
Try it below: drag between the two islands, or tap the bridge once it exists.
1Islands with no choice
The island in the middle below shows a 4, and it has exactly two neighbours. The most bridges it could ever receive is two from the left island and two from the right — 2 + 2 = 4. There is no other combination that reaches 4, so both connections are forced into double bridges before you even have to think about the other islands. This is the workhorse deduction: whenever a number equals the maximum its neighbours can supply, nothing is optional.
2Let the no-crossing rule choose for you
Below, the top pair of islands is already connected by a single bridge, and a double bridge already runs down the middle column. Try dragging the bottom-left island straight across to the bottom-right one — the board refuses it, because that bridge would cross the double bridge already there. Once that option is gone, each of those two islands has exactly one place left to send its one bridge: straight up.
3The trap almost every guide skips
This is the deduction that separates people who can read the rules from people who can actually finish a hard board. Below, the bottom two islands are already joined by one bridge. Both top islands show a 1, and they happen to face each other directly — so the tempting first move is to connect them to each other. Try it.
It works, locally: both show a 1, and one bridge between them satisfies both completely. It is still the wrong move. Both top islands now have their one and only bridge spent on each other, which was their only other route down to the bottom pair — so the bottom two islands can never reach their own numbers again, no matter what you do next. Undo it, and connect each top island straight down to the island below it instead: now every bridge leads somewhere, and the four islands end up as one network instead of a satisfied pair next to a puzzle with no way to finish it.
4Put it together
One full puzzle, generated the same way every puzzle in Pontis is. No hints, no help — everything you need is the number on each island and the three ideas above.
Everything above scales up: every puzzle in Pontis is built the same way, from a first-bridge introduction to boards that take these three ideas a few dozen moves deep. None of them were designed by hand.