How do you play Bridges (Hashi)?
Each circle is an island, and its number says how many bridges must end there. Join the islands with straight bridges, across or down. Two islands can share one bridge or two, never more. Bridges may not cross each other or pass over an island, and when you finish, every island must be connected to every other through the bridges.
Choose a 7 × 7 grid with 10 islands, or 9 × 9 with 16. Tap an island, then a neighbour, to build a bridge. Do it again for a double bridge and a third time to take it away. You can also drag from an island toward a neighbour. On a keyboard, the arrows move between islands; Enter picks one, and an arrow then builds that way.
How is your Bridges Puzzle time calculated?
Your result is the time from Start until every island has its number, no bridges cross and all islands are joined. Next to it are the times you pressed Check, which marks any bridge that isn't in the answer (or is one too many), and Hint, which builds one right bridge or fixes a wrong one. An island turns red when it has more bridges than its number. A bridge that would cross another is refused, with a note saying why.
There is no rating, because no published typical time exists for puzzles built like these. The larger grid has more islands and far more ways to go wrong, so it takes several times as long.
How do you solve a Hashi puzzle?
- Full islands first. An island needing twice as many bridges as it has neighbours takes a double bridge to each: an 8 always does, and so does a 4 in a corner with only two neighbours.
- Nearly full islands next. One short of that, it still needs at least one bridge to every neighbour. A 7 has a bridge in all four directions, and a 3 in a corner has one to each of its two neighbours.
- Don't cut a pair off. Two 1s next to each other can't be joined to each other: they would be finished and cut off from the rest. The same goes for a double bridge between two 2s.
- Watch the crossings. A bridge you are sure of rules out every bridge that would cross it, which often leaves a neighbouring island with only one way to go.
- Keep the whole map joined. Near the end, a group of islands whose numbers are all used up must include every island. If it doesn't, one of its bridges is wrong.
Does every Bridges puzzle have exactly one answer?
Yes. Each game grows a new network: one island, then a bridge and a new island at a time, then a few extra bridges to make loops. No two islands sit side by side, so each is easy to tap. The network is kept only if a solver using the moves above, with no guessing, can find every bridge from the numbers alone. The site's tests check hundreds of puzzles this way and count their answers by trying every arrangement: always exactly one.
What does Hashiwokakero mean?
Hashi o kakero is Japanese for "build bridges!", the name the puzzle publisher Nikoli gave it. In English it appears as Bridges, and The Times prints it as Hashi. The puzzle is the same under every name.
For another puzzle about drawing lines, try the One Line Puzzle; for finding a path, the Maze Game.