Hadean Chess is played like standard chess except for following modifications:

1. Flexible Castling - The king can castle by moving 1 to 5 squares towards rook. The rook always ends up next to the king on the other side as in standard chess. The same rules: cannot castle out of check, king cannot pass over squares attacked by enemy etc apply.
   The choice of castling depends on whether it is more desirable to immediately have the rook in the center file or the king tucked away at the wing.
    
   Note: When carrying out 1 step castling, Zillions pops up a box asking to choose a move.
   The second move indicating kings move AND the rook to move to king square (Rook x king) is the castling move.
    
   
2. The standard pawn move is modified slightly – it can now move 1,2, or 3 squares initially. It can also move two spaces forward if it moved only 1 space or captured from original position.
    
   En-passant is modified to accommodate this. A pawn that attempts to bypass an enemy pawn by making a double or triple move is captured En-passant.
    
   This En-passant only applied to standard pawns. Ninja pawns cannot capture or be captured this way.
    
   
3. Pawns and ninja pawns promote in the last rank to any piece.
    
   
4. The larger 12x12 board, and the movement of the new pieces: the Ninja Pawn, the Wazir Knight, The Ferz Knight,the Ferz Sorcerer, the Wazir Sorcerer, Flying Warmachine, and Flying Elephant.

For full details of the moves please see: http://chess.computerwebservices.net/hadean.php