How to Make Your Own Hashi Puzzle

Designing a Hashi puzzle is a fun way to understand the bridges puzzle from the inside, and it's easier than it looks once you know the trick: build the solution first, then hide it. Instead of scattering numbers and hoping they work, you draw a valid bridge network, label each island with its bridge count, and erase the bridges to leave the puzzle. This guide walks you through how to make your own Hashi (Hashiwokakero) puzzle by hand, and how to make sure it has exactly one logical solution. To see how solvers will approach it, read how to solve Hashi puzzles first.

Step 1: Place your islands

Start with grid paper and mark where your islands will go, the points you'll connect. A few guidelines:

• Use a small grid for your first puzzle, say 7×7, with 8 to 12 islands, the same scale as our easy puzzles.
• Line islands up in rows and columns. Bridges only run horizontally and vertically, so each island needs at least one other island sharing its row or column to connect to.
• Leave space. Don't crowd islands so tightly that there's no room for the network to breathe.

Step 2: Draw a valid, connected bridge network

This is the heart of it. Connect your islands with bridges, drawing the solution you want, while obeying every rule:

• Bridges run straight, horizontal or vertical only.
• At most two bridges between any pair of islands.
• No bridge crosses another bridge or passes through an island.
• Every island is connected into one single network, no island left stranded.

Take your time and make sure the whole thing links up. This finished network is your answer key, so keep a copy.

Step 3: Label each island with its bridge count

Now count. For each island, add up the bridges touching it (a double bridge counts as two), and write that number inside the circle. An island with one single bridge becomes a 1; one with two doubles becomes a 4; the busiest possible island, with doubles in all four directions, is an 8.

When you're done, every island has a number, and those numbers exactly describe your network. That's your puzzle, almost.

Step 4: Erase the bridges

Rub out the bridges, leaving only the numbered islands. What remains is the puzzle a solver sees: a scatter of numbers, with the connections hidden. The solver's job is to rebuild the exact network you drew, using only the numbers and the rules.

Step 5: Test for a single solution

This is the step that makes or breaks a puzzle. A good Hashi has exactly one solution reachable by logic, no guessing. To check yours, set your answer key aside and solve the puzzle fresh, as if you'd never seen it:

• If you can rebuild your network using only forced bridges, elimination, and connectivity, with no point where you'd have to guess, the puzzle is solid.
• If you reach a spot where two different bridge arrangements both fit, your puzzle is ambiguous. You'll need to adjust it.

To fix ambiguity, tweak an island or two, move an island, add one, or change a connection, so the numbers force a unique answer. A couple of rounds of adjusting is completely normal.

Tips for better Hashi puzzles

• Include a few high-value islands (like a 6 or 8). They create forced bridges that give solvers a foothold and keep the puzzle solvable without guessing.
• Mind the connectivity. Make sure your network is genuinely one connected group; a stray isolated island makes the puzzle impossible.
• Avoid lonely 1s facing each other, two 1s that could only bridge each other create an unsolvable dead end.
• Scale up gradually. Once you can make a clean 7×7, try a bigger grid with more islands, the same way our difficulty levels ramp up.

Put your puzzle to the test

The real reward is watching someone rebuild your hidden network from nothing but numbers. Once you've made a few by hand, you'll appreciate the construction behind every grid you play. Want well-made examples to study? Solve a range of ours, from easy to the Einstein level, and notice how every island count points to exactly one answer. The solving guide sharpens the instincts that make you a better designer, too.