Bridges Island Puzzle
Bridges Island Puzzle is a number-and-network logic game played on a grid of open water. Each round island shows a number, and that number is exactly how many bridges must touch it.
It belongs to the Portable Puzzle Collection by Simon Tatham, with this puzzle coded by James Harvey together with Tatham himself. It plays in a browser tab with no install, and every new map is checked by a solver, so you can always reason your way to the answer.
How to play Bridges Island Puzzle
Bridges are straight lines that run across or up and down, never at an angle. They cannot cross one another, and any two islands can share at most two bridges. A double bridge adds two to the count of both islands it joins.
Drag from an island toward a neighbor to lay a bridge. Do it again to make it double, and once more to take it away. The puzzle is solved when every island has its exact number and you can travel from any island to any other.
If an island has too many bridges, or can no longer reach its number, it turns red. A group of islands that is sealed off from the rest also shows up in red, so mistakes are easy to spot.
Controls
| Action | Keyboard | Mouse | Touch |
|---|---|---|---|
| Add, double or remove a bridge | Ctrl + arrow, or Enter then an arrow | Drag from one island toward another | Drag from one island toward another |
| Mark two islands as not linked | Shift + arrow | Right-drag between islands | Press and hold, then drag |
| Lock a finished island | Space | Click the island | Tap the island |
| New, undo, redo | N, U, R | Menu buttons above the map | — |
Tips
- Start with islands whose number equals twice their number of neighbors. An 8 in the middle needs double bridges in all four directions.
- Corner islands have only two possible neighbors. A 4 in a corner means two double bridges, with no room for doubt.
- Look for islands that would cut off a pair. Two 1s next to each other can never link only to each other, or they would form a closed group.
- Use the not-linked mark whenever you rule out a connection. It keeps the map clear and stops you from adding that bridge later by mistake.
- Lock islands as soon as they are complete so a stray drag cannot change them.
If you like Bridges Island Puzzle, try these
Train Track LogicConnecting points under clue counts carries over, as you lay one rail route from A to B that matches row and column numbers.
Net Pipe PuzzleHere the goal is one joined network too, made by turning pipe tiles until each links back to the source.
Questions
How do you win at Bridges Island Puzzle?
Every island needs exactly as many bridges as its number, and all islands must join into one connected network. When both are true, the puzzle flashes to show it is solved.
Can I change the size or difficulty?
Yes. The Type menu lists preset maps from 7x7 up to 15x15 at several difficulty levels, and Custom lets you adjust settings such as whether loops are allowed.
Does Bridges Island Puzzle work on a phone?
Yes. Short drags lay bridges, and pressing and holding works like a right-click for marking islands as not linked.
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