The 4 3x3 boards on the corners are called attack boards and can move along the edges of the chess board. The centre 2x8 board is called the main board and cannot move. All the pieces can move on and off of these boards with their usual moves.
All F.I.D.E. chess rules apply here with a few exceptions: No en passant except on the main board, castling is only allowed when the attack boards are in the starting position, pawn promotion is only available on the main boards 8th ranks, and as you can see the two space starting move for pawns is only available on the main board and no where else.
Attack boards: the attack boards aren't attached to the main board and can move if you please. The movement of an attack board is limited and can only be moved once a turn, instead of moving a chess piece. The limitations are as follows: you cannot abandon another attack board:
This move couldn't be made because it leaves the attack board out in the open. An attack board must always touch another board, be it the main or an attack board. It cannot abandon itself either.
Next, the attack boards can only move to a space that corresponds in black white square fashion:
This move cannot be made because the lineup of the squares is wrong. The white squares are lined up with each other, same with the black, and this is illegal. Keep this in mind when moving attack boards.
Third, turning corners can only be made from a certain position:
This is the only corner turning move (check notes section at the end of the rules). It must be done in some form of the example above.
Fourth, you can make a move called a d-jump:
This move may be made in a situation similar to the above example.
Finally, each player has their own two attack boards. You must find a way to identify these boards. You may only move your own attack boards.
Notes: When making a corner move you may encounter that it is not possible based on the lining up of the squares rule. However, a cornering move may be done by any attack board so it may have to look like this:
Since the board in question cannot get to the exact corner to make the move it can corner from as close to the corner as it can get.
Well, I hope you have a great time playing this great variant. Set up your pieces as usual and play!