Hashi Puzzle

How to Play Hashi (Bridges)

Hashi — also known as Bridges or Hashiwokakero — is a logic puzzle about drawing. A set of islands sits on a grid, each one stamped with a number. Your job is to connect them all by drawing bridges, obeying four simple rules:

• The number is the total. An island marked 3 must connect to exactly 3 bridges when the puzzle is finished. Tap an island to see it turn amber as it is satisfied.
• Straight lines only. Bridges run horizontally or vertically between two neighboring islands — and only between islands that are closest neighbors in their row or column, with no other island in between.
• Up to two per pair. A single pair of islands can be joined by at most 2 bridges. Tap the same gap again to cycle 0 → 1 → 2 → 0.
• No crossing, no passing. Bridges may never cross one another and never cut through an island. Every bridge travels the empty water in between.

On GridPaw, easiest way to play: tap one island, then tap a neighboring island to place a bridge between them — keep tapping that second island to cycle the pair up to 2 and back to 0. You can also tap the gap right between two islands to cycle that bridge directly. Islands turn red when their bridge count is wrong, and amber when matched. The puzzle is solved when every island is matched and all islands are connected into one network.

What Is Hashiwokakero? Hashi vs Bridges vs Hashiwokakero

Hashiwokakero (橋をかけろ) is Japanese for "let's build bridges" — and it is the original name of the puzzle you are playing. It was invented in 1990 and first appeared in Nikoli puzzle compilations, the same Japanese publisher that popularized Sudoku, Kakuro and Slitherlink. The name is a mouthful in English, so most publications shorten it to Hashi ("bridge") or simply call it Bridges.

All three names describe the exact same game with identical rules: island numbers, horizontal and vertical bridges, up to two bridges per pair, no crossing, one connected network. If you have solved a "Bridges" puzzle in one app and a "Hashi" puzzle in another, you have solved the same puzzle twice. At GridPaw we use the short, searchable name Hashi, but you will see the identical grid published elsewhere as Bridges or Hashiwokakero — same islands, same water, different sticker.

Hashi vs Sudoku

Sudoku is a grid of digits where every row, column and box gets the numbers 1–9 exactly once. Hashi is a different breed of logic: it is a graph puzzle. There is no grid of numbers to fill — there is a network of islands and bridges, and the numbers are given. The logic lives in counting connections, not placing digits.

That difference changes how you think. Sudoku solving is mostly elimination: candidates get crossed out row by row. Hashi solving is planning: every bridge you add affects two islands at once, and the final connectivity rule means you must think about the whole archipelago, not just one island in isolation. Many players find Hashi the more relaxing of the two — no arithmetic, no candidate notation, just drawing clean lines until the map clicks together. They are both pure logic, but Hashi exercises a very different part of the brain.

Hashi Tips and Strategy

New to Hashi? These patterns will get you through every GridPaw puzzle:

1. Read the degree, not the board. An island's number is its total edge slots. A 1 island with only one neighbor can only be satisfied by a double bridge to that neighbor — place it and one neighbor is instantly complete.
2. Watch the corner islands. Corner islands have at most two bridge directions, so a corner 3 is already half-solved: it must take both directions and at least one must be a double bridge. Count the remaining slots carefully.
3. Finish a degree-1 island early. An island that still needs exactly 1 bridge can take it from any neighbor — but while it is waiting, its neighbors must treat it as one slot. Lock it the moment its options narrow.
4. Think connectedness before you finish. Bridges must not just add up — the finished network has to be one connected graph. Before doubling a far-flung pair, check that every island can still reach the rest of the map. Isolated bubbles are the classic endgame trap.
5. Use two bridges as anchors. A double bridge is the strongest connection on the board: it consumes two slots on both islands at once and is almost impossible to reroute later. Prefer completing doubles early, while single bridges stay flexible.
6. Let the red tint guide you. When an island goes red, its bridges do not add up yet — undo and recount. Land on amber and that island is correct, so move on to the next one.