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This page is written by the game's inventor, Jörg Knappen.

Sai squad

The Sai Squad is a very experimental army for Chess with Different Armies. It is the first game known to the author that features the Bishop-Quintessence compound.


On the Rook's squares, there is the classical Rook. On the Knight's squares, there are two Knaves, on the Bishop's squares are two Diamonds. On the Queen's square is the Sai, a Bishop-Quintessence compound. The King and the pawns are the same as in FIDE chess.


The Rook, the Pawns, and the King move as usual. Pawns can promote to any piece except King present in the initial setup of both armies.

The Knave is a six-directional piece, moving and capturing as forwardmost or backwardmost Knight or sideways Dabbaba (ffbbNsD in Ralph Betza's Funny Notation). It was found and named by Charles Gilman in Knavish Chess. A knave on b1 can move to a3, c3, and d1. The Knaves are both colourbound and bound to one half of the available ranks---each Knave can visit one quarter of the squares on the board. The Knave is worth 2.25 pawns or 3/4 of a Knight.

The Diamond (also known as Kylin from Chu Shogi or as Duke) is a compound piece of Fers (moving one square diagonally) and Dabbaba (jumping two squares orthogonally. The Diamond is worth the same as a Bishop or a Knight, but I don't assign a pair bonus for having two Diamonds.

The Sai is a compound piece of the Bishop sliding diagonally and the Quintessence making consecutive Knight moves in an orthogonal zigzag pattern. The Sai is featured the first time in a chess variant here (as far as the author knows). It is names after Fujiwara no Sai, the ghost in the goban in the manga Hikaru no Go. Go is a japanese homophone of the number 5 giving a reference to the Quintessence. My assement is that a Sai is worth 2 Pawns more than a Queen.


All rules for Chess with Different Armies apply with the following important exception: Move Zero Any army playing against the Sai Squad advances their pawns on files d and f by one step. This move prevents a mate in one by the Sai. In special, this applies to both sides when both black and white are playing the Sai Squad.


The move zero rule is here to repair a serious flaw in the original version of the game: "I discovered a quintessential mate-in-one which invalidates this game completely: Sai d1--e3 with double check and mate. It is a double check because there are two quintagonal paths from e3 to e8: e3..d5..f6..e8 and e3..f5..d6..e8. The Black king cannot move, the double path cannot be blocked in a single move, and the Sai cannot be captured. Game over."

This rule comes originally from Ubi-Ubi Chess and its application to the Sai Squad was proposed in a comment by Chris Chradle.

The Sai immediately eyeballs the two squares b7 and f7. Armies where the square b7 is undefended cannot compete against the Sai squad (f7 is always defended at least by the King). The Sai has a huge forking power, therefore the oppnent must care for hanging pieces. On the other side, the queen can keep attacking the Sai to drive it back: he will retreat because she is weaker and he cannot afford being traded for a queen.

A pawn on b4 is an effective measure against the devolopment of the Knave on b1. Also, the Knaves and the Diamonds both want to develop to c3/f3 but only one of them can sit there.

A pair of Diamonds can mate a bare King without assistence. The Sai is stronger than a Queen but still needs assistance to enforce checkmate. There is an exception to this when the King is already on a corner square.

I call this army very experimental because of its very unusual material balance: It features a super-queen piece and a piece significantly weaker than the Knight. I am also not really confident of the army's value, though I tried to make it close to the value of the FIDE chess army.

Ralph Betza did an experiment with a super-queen army featuring the Amazon in his Amazon army. You may want to try this army as an opponent to the Sai Squad.

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Jörg Knappen.

Last revised by Jörg Knappen.

Web page created: 2013-01-14. Web page last updated: 2021-02-14