Bridge Islands is a connection puzzle. Round islands carry numbers; you build bridges between them so that every island has exactly as many bridges as its number and you can walk from any island to any other. Every puzzle here is generated fresh and checked by a solver so that it has exactly one answer.
How to play
The rules.
- A bridge runs straight, horizontally or vertically, between two islands in the same row or column, and it cannot pass over another island.
- Two islands can be joined by one or two bridges, never more.
- Bridges never cross each other.
- Every island has exactly as many bridges as its number.
- When you are done, all islands form one connected network.
Building bridges. Tap any empty cell between two islands: the whole stretch between them becomes a single bridge. Tap again for a double bridge, again to switch to the crossing direction if that cell also lies between two islands vertically, and once more to clear. You can also select a cell and use Bridge ×1, Bridge ×2 or Erase. On a keyboard, 1 and 2 set the bridge count, 0 clears it, and the arrow keys move between cells.
Mistakes and help. An island with more bridges than its number is outlined in red, and so are bridge pieces that were broken by a crossing bridge or that lead nowhere. Hint fixes a wrong piece if you have one, otherwise it builds one correct piece. Undo takes back your last change, one whole bridge at a time. The timer and the number of hints you used appear when you finish.
Difficulty. Choose under Difficulty at the top; New puzzle creates another grid at that size.
| Level | Grid | Islands |
|---|---|---|
| Easy | 7 × 7 | about 8 |
| Medium | 9 × 9 | about 13 |
| Hard | 11 × 11 | about 20 |
Strategy
Start where there is no choice. An island whose number equals twice the count of its neighbours needs a double bridge to each of them: a 4 in a corner with two neighbours, a 6 on an edge with three, an 8 in the middle. A 1 or 2 with a single neighbour is just as forced.
Count the room. If an island’s neighbours can supply exactly the number it needs, every one of those bridges is certain. If a neighbour is already full, that direction is closed and the remaining directions must carry the rest.
Isolated pairs are forbidden. Two 1s facing each other cannot be joined, and two 2s cannot be joined by a double bridge, because that would cut them off from the rest. The connection rule removes options long before the counts do.
Mind the crossings. A bridge blocks every corridor it passes through. Once a long bridge is certain, the islands on either side of it lose that direction, which often settles them.
If you enjoy Bridge Islands, try Bulls and Cows or Color Code next.
