How to play
Bridges is a logic puzzle on a square grid. Some cells hold round islands, each with a number from 1 to 8. Join the islands with bridges until the puzzle follows four rules:
- Bridges run straight across or straight down, never diagonally, and only between two islands that can see each other with no island in between.
- Two islands can share one bridge or two, never more.
- Bridges never cross each other or pass over an island.
- Every island ends up with exactly as many bridges as its number, and all islands form one connected network.
A finished island turns solid green with white text. An island with too many bridges turns red and shows how many it has to lose, for example +1. Every puzzle has exactly one solution, which you can always reach by reasoning, without guessing.
Controls
- Mouse or touch: drag from an island toward a neighbour and let go; the direction of the drag decides, so you need not land on the other island. You can also click or tap one island and then the other. Doing it again makes a double bridge, a third time removes it.
- Bridges: clicking or tapping a bridge, or the empty gap between two linkable islands, changes it the same way.
- Keyboard: the arrow keys move the highlight from island to island. Shift plus an arrow, or Space followed by an arrow, builds or changes the bridge in that direction. Delete clears all bridges of the highlighted island.
- Other keys: U and Y (or Ctrl+Z and Ctrl+Y) undo and redo, C checks, H gives a hint, P pauses, N opens the new puzzle menu and F switches to full screen.
Check marks every bridge that is not part of the solution with a red ×. Hint makes one move for you: it removes a wrong bridge if there is one, otherwise it adds a bridge that follows from the numbers and says why. The clock stops while the game is paused or the tab is hidden, and best times count only puzzles solved without hints.
Solving techniques
Three ideas solve most puzzles, and the difficulty levels are built on them.
- Counting. Compare what an island still needs with the room its neighbours have left. If an island needs n more bridges and the gaps to its neighbours can take m in total, each gap must get at least n − (m − its own room) of them. A 4 in a corner has only two neighbours, so it needs a double bridge to both.
- Blocking. A bridge closes every gap that crosses it, and a finished island has no room left. Each new bridge lowers the room around it and often starts a new counting step.
- Connecting. All islands must end up in one network, so you may never close off a group. Two 1s can never be joined to each other, two 2s never by a double bridge, and a group of linked islands with only one way out must use that way.
Easy puzzles can be solved by counting and blocking alone. Medium puzzles need the connecting idea at least once. Hard puzzles need a what-if step: assume a bridge, follow the consequences until they contradict each other, and you have proved the opposite. The game gave each puzzle its level by solving it with exactly these steps.
How the puzzles are made
Each puzzle started as islands scattered so that no two touch, not even diagonally, joined by a random network of bridges that never cross. Each island got its bridge total as its number. A solver then searched every possible arrangement of bridges and kept only layouts with exactly one solution, and a second, independent program checked each kept puzzle again. There are 100 puzzles for each size and level, 900 in all, and the game shows each one turned or mirrored in one of eight ways, which keeps the solution unique and the difficulty the same.
Tips and strategy
- Start with islands whose number tells the whole story: a 3 or 4 in a corner, a 5 or 6 on the edge, and any 7 or 8. A 7 needs at least one bridge to each of its four neighbours, an 8 a double bridge to each.
- After every new bridge, look at the islands around it, because their room has just changed.
- Watch pairs of 1s and of 2s that face each other: joining them the wrong way would close off a group.
- When you are stuck, pick a gap with two possible answers and test one in your head, with Undo ready.
Frequently asked questions
Is this the puzzle also known as Hashi?
Yes. Bridges is also called Hashi, from the Japanese word for bridge, and the rules are the same. The puzzle first appeared in a Japanese puzzle magazine in 1990, after an earlier form in 1989.
Can I play on a phone?
Yes. Each island reacts to touches up to about one grid cell away, and the page does not scroll while your finger is on the board. Full screen gives the 13×13 board more room.
Sources
- Wikipedia contributors (accessed 25 October 2026). Hashiwokakero. Wikipedia. Encyclopedia article. The Japanese name and its meaning, and the first publication in September 1990 after an earlier form in December 1989.