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Rose Chess XII

Introduction

Dedicated to Ralph Betza

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.

War Machine - This piece moves 1 square orthogonally or leaps 3 squares orthogonally. Greg Strong introduced this piece, calling it a Scout, in Brouhaha and Hubbub. Represented here by a Siege Engine on three wheels.

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 developement and sharp tactics. Someday, in the distant future, I may try to 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: I wanted to believe 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. My Spotted Gryphon 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.

P=100, N=300, WM=275 to 325, B=375, SG=400 to 500, NN=550, R=600, Rose=600 to 800, Q=1050 to 1100 in endgames on the 12x12 board. The WM = War Machine has a weak Wazir component and a strong "3-leaper" component. Difficult to compare this new piece with the Knight, which has a thousand years of history. Accurately assigning a value for the Rose is even more difficult. I am hoping that this (low density) game will offer players the opportunity to make such an estimate. The SG = Spotted Gryphon should be worth about half as much as the original Gryphon. The value of the NN = Nightrider is subject to debate. I choose to value the Nightrider at around 90 percent of a Rook in the endgame. The Queen should still have value equal to a Rook and a Bishop and a Pawn.

Forget about Ralph Betza's Rook - locked away in a corner of the board, with a positional penalty reducing its assigned value. He used selected portions of his extensive theory (developed to accurately balance different pieces through the opening, middle game and endgame) to construct Chess with Different Armies. I am simply trying to estimate relative endgame values of pieces, with an arbitrary 100 points for the constantly changing value of a Pawn crossing the board. I consider 5 Rooks equal to 8 Bishops on any square board. That gives the Bishop a tiny edge over the Knight on an 8x8 board, where I follow a STANDARD table of values and let 5 Knights equal 3 Rooks. Riders like the B, R, Q, NN increase in value as the board gets larger. As for the performance of these pieces in your own games: "mileage may vary", as the car manufacturers like to say.



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By David Paulowich.
Web page created: 2007-05-28. Web page last updated: 2007-05-28