What is Hashiwokakero?
Hashiwokakero is a Japanese logic puzzle first published by Nikoli in 1990. The name roughly means "build bridges", and that is the whole game. Numbered islands sit scattered on a grid, and you draw bridges between them until every island has exactly the count it asks for. Most players shorten the name to Hashi, and English puzzle books often print it as Bridges.
Hashi has lasted for the same reason sudoku has. The rules take under a minute to learn, no arithmetic or vocabulary is required, and every deduction is airtight. A well made board never asks you to guess. It asks you to notice.
Hashiwokakero rules
Every island shows a number from 1 to 8, which is exactly how many bridges must connect to it. Bridges run horizontally or vertically in straight lines. They cannot cross other bridges or pass through islands, and at most two bridges may join the same pair of islands.
There is one more rule that new players often miss. When the puzzle is finished, every island must be reachable from every other island across the bridges, so the whole board forms a single connected network. Plenty of tempting moves satisfy the numbers but seal off a group of islands, and the connection rule is what forbids them.
A quick example: an island marked 3 in a corner has only two directions available, so it needs at least one bridge in each. An island marked 8 needs double bridges in all four directions, no thought required.
Strategy and tips
Start with the forced islands. An 8 always takes double bridges in all four directions. A 4 in a corner fills both of its directions with doubles, and a 6 on an edge does the same with its three. Whenever an island's number equals twice the neighbours it can reach, every one of its bridges is decided.
Next come the nearly forced islands. A corner 3 must send at least one bridge each way, and an edge 5 must reach all three of its neighbours. Draw every bridge you are certain of, because each one blocks crossings and shrinks the options for the islands nearby.
Use the connection rule as a solving tool, not only as a win condition. Two islands marked 1 can never join each other, because that pair would be cut off from the rest of the board. The same goes for a pair of 2s joined by a double bridge. On harder boards, asking which bridge keeps a region connected is often the deduction that breaks the deadlock.
Work in passes. Every certain bridge changes the arithmetic around it, so a board that looked stuck at the start usually falls once you sweep it again.
The daily Hashi puzzle
A new set of boards arrives every day at midnight UTC: easy, medium and hard, plus an expert board as an optional bonus. Everyone plays the same boards on the same date, in the browser, no download needed.
Every daily board is produced by our generator and proved by a solver to have exactly one solution before it is published. Difficulty is graded by the reasoning a board demands rather than by its size. Easy asks you to spot forced moves, medium chains those moves together for longer, hard needs the connectivity argument, and expert is built so that routine rule following will not finish it.
Completing easy, medium and hard finishes your day and keeps your streak alive. The expert board never threatens the streak. It only upgrades a finished day to a clean sweep.
Hashiwokakero FAQ
Does every daily Hashi have exactly one solution?
Yes. A board is only published once our solver proves the clues admit a single solution. If you reach a position that satisfies every rule, it is the solution.
Is Hashi the same game as Bridges?
Yes. Hashiwokakero, Hashi and Bridges are all names for the same puzzle. Hashiwokakero is the original Japanese name used by Nikoli, and English publishers often prefer Bridges.
How long does a puzzle take?
Easy is a warm up of a couple of minutes once you know the standard openings. Medium and hard usually take somewhere from five to fifteen, depending on how quickly the key deduction shows itself. Expert varies the most by design, and the same board can fall in one minute for one player and twenty for another.
Do I ever have to guess?
Not on easy, medium or hard, which always fall to direct deduction. Expert is deliberately pitched beyond the standard techniques, so you will sometimes need to test a hypothesis and follow it. Because every board has a single solution, a wrong hypothesis always runs into a contradiction that teaches you something.
When does the new puzzle arrive?
At midnight UTC, all four boards at once.