Hashiwokakero is a Japanese phrase that translates directly as 'build bridges'. The game is played on a rectangular board. Some board cells contain encircled numbers from 1 to 8 (inclusive) - representing islands. The rest of the board is empty at the beginning of the game.
The goal is to connect all the islands by building a series of bridges between them. The bridges must respect these criteria:
they must be straight lines, beginning and ending at distinct islands.
they must not intersect with any other island or bridge.
they can be placed only horizontally or vertically.
a pair of islands is connected by two bridges at most.
the number on the island must match its number of connected bridges.
the bridges must connect all islands in a single connected group.
To draw a bridge between two islands, click on one of the islands and then click on the other one. By repeating the process with the same islands, you can draw a second bridge between them. Repeat one more time to delete both of those bridges.