IntroductionThe Xiang Qi army has always been regarded as weak, which could be why there has been so little attempt to extend it to 3d. The XQ Elephant suffers particularly on a cubic board. The 7 cells out of a 5x9 side of the River (about 2 in 13) extrapolates to 13 on a 5x5x5 half of a cubic board (about 2 in 19). Even an Elk (Elephant plus the 2:2:2 Eunuch) gives the same number of cells as a Dabbaba, 27 (about 3 in 14). For years this delayed my own attempt at a cubic Xiang Qi.
Then I had a brainwave. Expanding to 3d triples the number of possible oblique pieces, so I decided to dispense with non-coprime steppers altogether in favour of stepping forms of all three of these. It is the fact that the extra two are triaxial that gives the variant its name. I also decided to expand orthogonal pieces to Queenwise to maintain only one type of radial lacking long-range pieces (and bring in the King familar to non-Chinese). An alternative would be to add Yang Qi diagonal pieces, but I did not want to either increase piece density too much or lose the symmetry of the XQ board.
SetupThe 10 ranks are 5x5 boards laid vertically. Note that each King is in the middle of its rank. Note also how Barons are brought forward relative to where the XQ Ferz starts so as not to obstruct Knights' defence of Sextons from Cannons - an analogue to Rooks defending Knights in XQ.
|The KING moves one step along the 6 orthogonals and 12 standard diagonals and must be kept out of check. As the analogue of the XQ General it starts at the centre of the first rank.|
|The QUEEN moves any distance through empty intermediate cells along the 6 orthogonals and 12 standard diagonals. As the analogue of the XQ Rook it starts at the corners of the first rank.|
|The TANK moves like the Queen except that capturing requires exactly one intervening piece of either army, which is not itself captured. As the analogue of the XQ Cannon it starts halfway along the sides of the third rank.|
|The PRINCELING moves one step along the forward orthogonal and 4 forward standard diagonals and must be kept out of check. As the analogue of the XQ Point it starts on selected cells of the fourth rank, including orthogonally and diagonally in front of the Queens but not orthogonally in front of the Tanks.|
|The DUKE moves one step along the 6 orthogonals and 8 nonstandard diagonals (commonly called triagonals). It cannot lose the move as all its moves switch to the opposite Bishop binding. It starts beside the King on every same-rank orthogonal.|
|The BARON moves one step along 12 standard diagonals and 8 nonstandard diagonals. It starts on the second rank, leaving behind it a pass-through cell for Knights to cover Sextons threatened by enemy Cannons.|
|The Triaxial Qi KNIGHT is the multipath Stepping one also known as a Moo, a compound of Mao and Moa. It makes a 2:1:0 move comprising a King step of each kind in either order, requiring an empty intermediate cell along at least one route.|
|The Triaxial Qi SEXTON is a multipath Stepping one along the same lines. It makes a 2:1:1 move comprising a Duke step of each kind in either order, requiring an empty intermediate cell along at least one route. As the Sexton is bound to alternate cells, it is the nearest equivalent to the XQ Elephant. Note that a move of two successive Ferz steps is not allowed.|
|The Triaxial Qi NINJA is a multipath Stepping one along the same lines. It makes a 2:2:1 move comprising a Baron step of each kind in either order, requiring an empty intermediate cell along at least one route.|
RulesThe 3x3x3 cube of cells at the centre of each player's first three ranks forms a Fortress which King, Dukes, and Barons must not leave. In addition Kings may not share a file without an intervening piece.
The board comprises two 5x5x5 cubes. A Knight crossing from one to the other must make the orthogonal stage of that move first - i.e., move as a Mao. A Sexton doing so it must make the standard-diagonal stage first. A Ninja doing so must make the nonstandard-diagonal stage first. In all cases this is a restriction only on the crossing, and having made the crossing the piece may make either stage of its move first within the half of the board that it has entered.
When a Princeling crosses from its own half to the enemy half it is promoted to also move one step along any same-rank orthogonal or diagonal, 4 of each. This applies for the rest of its time in the game.
Check, Checkmate, and Stalemate are as usual.
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By Charles Gilman.
Web page created: 2006-10-31. Web page last updated: 2016-06-07