Sanaku is very similar to Hashiwokakero=> http://cross-plus-a.com/puzzles.htm#Hashiwokakero

The rules are the bit different though:

The goal is to connect all the islands(Circles) by drawing a series of bridges(Lines) between the islands. The bridges must follow certain criteria:

• Bridges must not cross each other.

• They may only run horizontally, vertically, or diagonally (45 degrees)

• At most one bridge connects a pair of islands.

• The number of bridges connected to each island must match the number on that island.

• The bridges must connect the islands into a single connected group.

• Some bridges are given initially, the goal is to find the remaining bridges

Note: Dotted gray lines show possible bridges, it's just to help you solve the puzzle, not a constraint

Here's a sample:

Donwload PDF version here: