Object: Fill the board with a chain of rods.

The 'chain' used in this game consists of straight tubes connected by 'links' (which are represented by coloured squares).

Starting move: Click the board anyhwhere to drop your first Link.

Normal drops:
Click the board on an empty position to the North, South, East or West of the previous click.
A new link will be displayed.
There must be only free positions between the current and the last link.
After your click the system automatically connects it with the new link by marking the connecting line with tubes.

There is a few special condition, however:
The connection between the last and the new link must be one unit longer or shorter than the previous connection.
E.g., a tube of length 3 must be followed by a tube of length 2 or 4.

You win if you have covered the whole board with the (uninterrupted chain.
You lose if you run out of moves.

Limitation: For technical reasons the maximum length of a connection (including the links) is nine.
This is no real limitation, however, since one can easily see that any connection of length ten or higher cannot be part of a solution for the given square boards.

Expert level:
Once you have solved the four variants, try to solve them with the least number of moves.
Here are the length of the shortest solutions known:
8x8 - 32 moves
9x9 - 52 moves
10x10 - 52 moves
11x11 - 65 moves