Overlink Shadows

The puzzle decided to lay low in the dark, but you can pull it out into the light in Overlink Shadows. To do this, you need to solve all the puzzles at thirty levels. The ultimate goal is the same - to connect two light points and thus cut darkness and darkness. An important condition - the path must pass through all the dark square, step on each one once. That is, you can not go back and go back to the same place. Slightly complicates the task and at the same time makes it interesting three-dimensional format. Each new route will be more difficult.