Hashi Bridges

Overview

A small archipelago becomes a network-planning problem in Hashi Bridges. Each numbered circle is an island, and its number tells you how many bridge ends must reach it. A bridge runs horizontally or vertically to the next visible island. You may draw one bridge or a pair between two islands, but bridges cannot cross or pass through another island. The entire archipelago must become connected: several perfectly numbered little groups do not count as a finished board. This combination of local arithmetic and global connectivity gives Hashi its character. A decision that looks sufficient for one island may cut off the only route to a distant corner. The bundled Bridges engine creates new puzzles and offers different sizes through its Type menu. Larger boards reward patience, because deductions tend to cascade from a single forced island.

How to Play

Press Play, then drag from an island toward another island in the same row or column. Repeat the same drag to change a single bridge into a double bridge; repeat again to remove it. Clicking an island without dragging marks it as finished, which is a bookkeeping aid rather than proof that it is correct. Touch users perform the same short drag. Use Undo to reverse a decision or Restart to return to the starting board. New creates another puzzle with the current settings. If a drag does nothing, check that the target is the nearest island in that direction and that no existing bridge blocks the line of sight.

Tips & Strategy

Begin with islands whose numbers nearly exhaust their available directions. An eight with four neighbours needs two bridges in every direction. A corner four with only two neighbours has the same forced pattern. Next look for places where completing two small islands would isolate them from the rest of the map. Keep at least one connection available until the whole network can join. Do not treat a crossed-out island as permanently settled: later connectivity deductions can reveal an earlier mistake. When a bridge would block the only route across a narrow channel, inspect both sides before drawing it.

Island Patterns Worth Memorising

Hashi rewards a small vocabulary of forced patterns. An island showing 8 with four neighbours takes double bridges in every direction, since doubles are the maximum allowed. A 7 works almost as hard: with only eight possible ends, at least one bridge must leave in each direction, so you can pencil in singles all round. The same arithmetic scales to the borders. A 6 on the board edge has only three neighbours and needs six ends, forcing doubles all three ways, while a 4 in a corner forces doubles both ways. A 3 in a corner, or any island whose number exceeds twice its open directions minus one, has at least one bridge fixed in every open direction.

A worked example: a corner 4 forces doubles to the island on its right and the island below. If the island on the right shows 3, two of its ends are now accounted for. When its remaining views are a 1 above and a 2 further right, and the upward bridge would complete the 1 while sealing that whole corner off from the map, the third end must go right instead. The general rule behind this: two islands that each need exactly one more end and can see only each other cannot be joined, because the connection would close a finished two-island component. Each must keep a route toward the rest of the archipelago.

Common Beginner Mistakes

New players often treat the finished mark as a guarantee, then build confidently on a wrong island. Another frequent error is satisfying every number in one region while quietly cutting it off from the rest of the board; the single-network rule fails only at the end, which makes the mistake expensive. Avoid assuming that an open line of sight implies a bridge, and remember that a bridge also blocks the crossing route between two other islands, so every placement removes options as well as adding ends.