What is Hashi?
Hashi is a logic puzzle where you link numbered islands with horizontal and vertical bridges so each island has as many bridges as its number and all islands end up connected. Two islands can share one or two bridges, and a bridge can never pass over another island or cross another bridge.
Its Japanese name, Hashiwokakero, means "build bridges", and it is also known simply as Bridges or Chopsticks. There is no arithmetic beyond small sums; it is a deduction puzzle about matching each number to the islands it can reach, so the rules are short like Sudoku but larger boards demand real thinking.
| Rule | Meaning |
|---|---|
| Number | How many bridges touch the island. A double bridge counts as 2 |
| Direction | Bridges run straight across or straight down, never diagonally |
| Count | The same two islands may share one or two bridges |
| No crossing | Bridges may not cross each other or jump over an island |
| One network | Every island must be reachable from every other along bridges |
Which bridges should I build first?
The classic opening is any island whose number is twice the number of its neighbours. A 4 in a corner, a 6 on an edge and an 8 in the middle need double bridges in every direction. Next look at islands one short of that, and islands with a single neighbour.
| Opening | What to build |
|---|---|
| Corner 4 · edge 6 · middle 8 | Two, three or four neighbours and a number twice that: two bridges every way |
| Corner 3 · edge 5 · middle 7 | Only one direction can be single, so every direction gets at least one bridge |
| Only one neighbour | All of the island's bridges go to that neighbour: one for a 1, two for a 2 |
| Two 1s | Joining a 1 to a 1 seals both off from everything else, so never link them |
| Two 2s | A double bridge between two 2s also seals them off, so at most one bridge |
| Full island | Once an island has its number of bridges, nothing more leaves it |
| Blocked path | A neighbour behind an existing bridge cannot be reached, so count only open directions |
| No closed group | A group of islands may not fill up while cut off from the rest, so keep a way out |
Does every puzzle have one answer? How are boards made?
Yes. Every board is generated fresh and only released after a solver confirms there is no other answer. The daily puzzle is built from a number fixed by the date, so everyone gets the same board.
The generator places one island on empty sea, then repeatedly stretches a straight bridge from an existing island and puts a new island at its end, keeping islands apart and bridges uncrossed, and now and then links back to an older island to form a loop. The bridges touching each island become its number. The solver then looks for another answer; if it finds one, a bridge where the two answers disagree switches between single and double, the numbers change, and the check runs again. All of this takes less than a second.
How do the difficulty levels differ?
Easy is 7×7, Normal is 10×10 and Hard is 13×13. Bigger boards hold more islands and call for trying a bridge in your head to find contradictions.
| Level | Size | What to expect |
|---|---|---|
| Easy | 7×7 | About twelve islands, solvable with the openings above alone |
| Normal | 10×10 | Over twenty islands; a few spots may need a one bridge what if step |
| Hard | 13×13 | Over thirty islands, with places where the openings stall and a what if step is needed |
| Daily | 10×10 | One board a day, the same for everyone, recorded in your daily streak |
What help is there when I get stuck?
Hint builds one correct bridge in gold, and Check shows broken islands and crossings in red. Undo takes back the last bridge you changed.
- Hint: fixes a bridge that is over the answer first; otherwise it builds a bridge that follows by deduction from your current board. The count appears on the result screen.
- Check: marks islands with too many bridges, groups that are full but cut off from the rest, and crossed bridges.
- Lighthouses: an island with exactly its number of bridges turns its badge gold and lights its lighthouse. Trying to build a crossing bridge is blocked and marked with an X.
Tips for solving Hashi faster
- Start at the edges. Corner and edge islands have few neighbours, so even modest numbers settle quickly.
- Compare what is left with where it can go. If an island's remaining number equals twice its open directions, all are double; one less, and all get at least one.
- Recheck neighbours after every bridge. A new bridge often blocks another path and narrows the choices of nearby islands.
- Never trap a group. A cluster of islands linked only to each other may not fill up. Its last exit must become a bridge.
- Try a bridge in your head. If assuming a bridge leaves some number short or over, that bridge goes the other way.
Controls
- Phone and tablet: press an island and drag toward a neighbour to build a bridge. You can also tap an island, then tap the neighbour or the water in that direction. Tapping a bridge or the channel between two islands cycles 1 → 2 → none.
- Mouse: drag and click work like touch, and a right click removes a bridge at once.
- Keyboard: arrows or WASD move between islands, Space selects one and arrows then change the bridge that way. Shift plus an arrow builds without selecting, Esc cancels, Z undo, H hint, C check.
Best times and the daily record are stored only in this browser and never sent to a server. When you finish, the sea turns to evening, every lighthouse sweeps its beam in turn and a sailboat passes under your bridges, and Share result turns your time and level into a picture card.