A bridge-building puzzle (Hashiwokakero). Connect numbered islands with horizontal or vertical bridges so that every island has exactly as many bridges as its number, and all islands form a single connected network.
How to play
Drag between two adjacent islands in a straight line to draw a bridge. Drag again on the same path to add a second bridge (maximum two per pair). Tap an existing bridge to remove it. Bridges cannot cross each other or pass through another island.
Objective
Connect all islands with bridges so each island's bridge count matches its number and every island is reachable from every other.
Strategy tips
An island numbered 1 in a corner has only one possible neighbour: draw that bridge immediately. Similarly, an island numbered 4 with only two neighbours must have two bridges to each.
Avoid isolating a small group of islands from the rest. Before drawing a bridge, ask whether it will cut off part of the board from the remaining islands.
Large islands (6, 7, 8) are almost always connected to every visible neighbour with at least one bridge. Start with them to anchor the network before resolving the smaller islands.