Rose Chess XII

Rose Chess XII begins with 48 pieces and 96 empty squares on a 12x12 board. Each army has 10 pawns, 8 standard pieces and 6 exotic pieces - all set up in the central 100 squares. The nightrider was almost a "standard piece" in chess variants several years back. Ralph Betza introduced the rose nearly 20 years ago, writing: "I think that circular pieces should be permitted to use the null-move, that is, to go around the circle and stop where they started." In this game I choose to replace it with a half-rose (halfling rose), making no more than four knight-leaps. This circular nightrider can still reach 32 squares on a large enough board. A pair of spotted gryphons controls 22 squares on the edge of the board, while the opponent's pair controls the remaining 22 squares. A pair of war machines completes the army. Greg Strong invented this shortrange leaper last year, calling it a scout. This game marks its fifth appearance.

Setup

This setup diagram illustrates a two-move game. The Black Rose delivers a single piece doublecheck, tracing paths through the squares (e4) and (f5). The Black Rose also attacks the escape square (h2). The White Rose may be a two-step Nightrider move away, but it cannot capture the Black Rose. White has been checkmated.

Pieces

Standard chess pieces, with the rules adapted to this larger board.

Nightrider - This piece repeats the knight's leap along a straight line. It may continue leaping like a knight in one direction until it captures a piece or is blocked from further leaping. See this page for a movement diagram.

Rose - This circular nightrider may make from 1 to 4 knight-leaps. See this page for a movement diagram.

Spotted Gryphon - This colorbound piece moves like a ferz and may also continue outward as a dabbabah-rider, until it captures a piece or is blocked from further leaping. It can reach all squares of the same color that a Gryphon can, with the advantage that its movement can only be blocked on those squares. See the CHAINSAW movement diagram below. [EDIT 2023] Except for the war machines, Rose Chess XII consists of pieces originally promoted by Ralph Betza. His Bent Riders page (2002 ) contains this remark: "A piece that makes an F move followed by an outwards Dababbah-Rider move looks interesting ..."

War Machine - This piece moves 1 square orthogonally or leaps 3 squares orthogonally. When Greg Strong introduced this piece, as the Scout, he gave it an initial Knight move to speed the game up. See Brouhaha and Hubbub. Represented here by a Siege Engine on three wheels - more appropriate than the two wheeled version used in Jumping Knights Chess.

CHAINSAW: moves like a Spotted Gryphon (red "X") or a Rook (red hollow square). A piece (not used in this game) which may be close to the RAVEN in value. [December 2008 note] Chainsaws replace Spotted Gryphons in SISSA CHESS XII - while Sissas replace Knights, Cardinals replace Roses, and Marshalls replace Nightriders. I am using a Dragon symbol for the Chainsaw piece, and considering changing the name to "Dragon". My "XII" variants are preliminary attempts to place an interesting mix of strong and weak pieces on a 12x12 board. In my experience the low (33 percent) piece density can lead to rapid development and sharp tactics. Someday, in the distant future, I might squeeze as many as sixty pieces into an "ultimate" 12x12 chess variant.

Rules

Castling is allowed, with the King moving two squares toward the Rook. Pawns can move two squares forward on their first move only, subject to "en passant" capture. They may promote to any piece of the same color (except a King or a Pawn) on the player's eleventh rank and must promote on the last rank. Promotion is not limited in any other way, one player may have as many as 12 Gryphons on the board. Victory conditions are the same as for modern chess. In particular, checkmate is a win and stalemate is a draw.

Betza's hopes for 16x16 variants with a variety of not-too-powerful pieces have run into a major obstacle. According to computer analysis in 2008 by H. G. Muller, King and one of: Bison (Camel+Zebra), Carpenter (DN), Commoner (FW), Half-Duck (HFD) are generally enough to force checkmate against the lone King on a 14x14 board. Yet these same pieces will often fail on a 16x16 board. Apparently they can no longer manage to force the lone King away from the center and into a corner. Depressing news, as I had hoped that the Half-Duck (which I renamed "Lion" in Unicorn Great Chess) could always force mate on a 16x16 board. Even worse news: Kangaroo (DN), Champion (WAD) and Woody Rook (WD) can each force mate on a 10x10 board, but fail on a 12x12 board.

Notes

Why a Duck? One thing I have learned from Betza is the importance of quoting the Marx Brothers. According to George Jelliss, the Duck may move like a Ferz or a Dabbabahrider. Adding the Ferz move has allowed this exotic piece to reach half of the squares on the board, instead of only a quarter. The Duck is called an Onager in Robert Shimmin's Scheherazade. Ralph Betza's invention, called the Spotted Gryphon in this variant, is another exotic piece with the ability to visit half of the board.

Betza used one Rose in this 16x16 variant and discussed the Gryphon's move. He next used a Gryphon, a pair of Nightriders and a pair of Roses in another 16x16 variant. I had forgotten that he placed [Wazir + Dabbabahrider] compounds in the corners of the board. Time to explain why I am limiting the (Half-)Rose to no more than four Knight-leaps and using a smaller board. Imagine that my game is being played on a 14x14 board, with "rank 0" at the bottom and "rank 13" at the top. Glancing at the mate-in-two diagram near the top of this page, we can see that:

Rose d6-f5-g3 is a clockwise check and

Rose d6-b5-a3-b1-d0-f1-g3 is a counter-clockwise check, taking six Knight-leaps along the same circular path. With this larger board and a "six-leaping" Rose, the illustrated mate involves a Rose triple check. Which leads to the conclusion that the Fool's Mate:

1.Pawn i4-i6 Rose f11-d12-b11-a9-b7-d6, making five Knight-leaps to deliver double check(mate), would only be prevented by the Black Gryphon occupying the (b11) square. But on a larger board, the Gryphons would probably be located somewhere else. So I find even the "six-leaping" Rose, which has been used in Charles Gilman's chess variant Irwell, too powerful to use in this game.

Estimated endgame values on the 12x12 board:

P=100, N=300, WM=270 to 330, B=360, SG=500 to 550, NN=540, R=600, Rose=660 to 760, Q=1080. Thus the Queen equals two Nightriders or three Bishops. The Rose should be worth at least a Bishop and a Knight. A Rose and a Nightrider working together should be worth at least two Rooks. Colorbound pieces like the Spotted Gryphon (or Slip Griffon) can be tricky - a pair may be equal to a Queen, while a solitary piece is worth less than half a Queen. The Knight and the War Machine are both short-range pieces with color alternating moves, which suggests that they may have equal value. Hopefully this low density game will provide opportunities to refine these estimates.

My comments on piece values have a narrow focus - they should not be directly compared with Ralph Betza's extensive writings (which cover piece values through the opening, middle game and endgame). For example, he reduces the assigned value of the FIDE Rook, because it starts the game locked away in the corner of the board. When I state that the Remarkable Rookies are collectively more powerful than other Chess with Different Armies forces - this is simply a prediction of their potential endgame value after surviving a long and arduous struggle.

Last revised by David Paulowich.