Maximum capacity: find routes that must be used
Start with islands that need many bridges but have few visible neighbours. The two-bridges-per-route limit can force an exact connection or just a minimum of one.
LEARNING CENTRE
Bridges: count what each island can still do
Use island totals to prove connections, crossing rules to remove routes, and connectedness to test the final network. The exercises distinguish a single bridge that must exist from a double connection whose exact count is known.
Rules you need at the board
Join nearest visible islands horizontally or vertically with zero, one or two bridges per route. A bridge cannot pass through an island or cross another bridge between islands. Each island’s number counts individual bridges, and all islands must belong to one connected network.
Four techniques to practise
Remaining capacity: subtract at both ends
Once bridges are placed, the opening neighbour count is no longer enough. Track what the island still needs and what each neighbouring island can still accept.
Crossings: one connection can remove another
A newly established bridge affects more than its two islands. Any possible route that crosses it disappears, potentially forcing a decision elsewhere.
Connectedness: do not finish a separate island group
A board can satisfy every number and still fail. Look for a route connecting each group to the rest of the board before spending its last available bridges.
Follow a practice collection
1. Count the available bridges
Compare full-capacity islands with islands that force only a minimum connection. Practise recording what is certain without prematurely choosing which route is double.
2. Track the consequences of a connection
Subtract bridges at both endpoints and remove crossing candidates. Use the resulting limits to explain a new forced connection elsewhere on the board.
3. Build one network, not several finished pieces
Combine numerical deductions with crossing and connectedness checks. Compare an apparently complete board with an actual connected solution, and identify the route a component still needs.
What the explanations can establish
A visible neighbour is only a possible route. Its remaining capacity and crossings may make it unusable. Correct island totals are insufficient without connectedness. Local capacity deductions need not finish every board; do not call a connection forced simply because it creates a tidy network.
Hints in this study area use the current marks. In Nonograms, Tents and Bridges, deductions assume earlier marks are correct; a local conflict stops the suggested step, but absence of a warning does not certify every mark. Minefield flags are never used as evidence. Cross Lights tests complete first-row choices and verifies the resulting plan.
Read a complete illustrated solve
Follow the original board walkthrough, with before-and-after diagrams and a final rule check. It is available without JavaScript.
Keyboard: Tab to controls and press Enter or Space. Board state saves locally; no account is needed.
DECISION LAB
A connected network can still leave three answers
Enumerate a six-island ladder to separate three different tests: correct counts, one network and a unique solution.
Test your prediction and follow the evidence →