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Ecutunnel and Ecumillstone

Introduction

These variants combine the ideas of my Tunnelchess and Twin-board Ecumemical Chess. The idea first struck me when I noticed that 32 can be seen as 2+(2*15), the first 2 representing a ruler and consort and the 15 representing the 15 possible pairings of 6 simple pieces. An obvious set of simple pieces is the three radial linepieces - Rook, Bishop, and Unicorn - and the three oblique leapers with maximum coordinate 2 - 2:1:0 Knight, 2:1:1 Sexton, and 2:2:1 Ninja. As a simple piece on its own is rather weak in 3d I decided to dispense with these and have an army of just 2 each of the 15 2-component compounds plus an Emperor and Empress, protected on each side by a rank of 16 Coheirs.

Setup

Ecutunnel has the board as shown, with Black's besieged character countered by White's divided army. Ecumillstone has it wrapped round to join the two White back ranks, so that the two armies besiege each other. Ranks are numbered 1 (White Emp-eror/-ress) to 6 (Black Queens) and lettered q (Black Emp-eror/-ress) to v (White Queens) for easy indication of which way Coheirs go. The top row of files are lettered a-d, the next e-h, the next i-l, and the bottom row m-p. As with Tunnelchess files admp form the Frame, files bcehilno the wall, and files fgjk the Tunnel.

Pieces

All-radial compounds
The EMPEROR moves one step in any of the 26 radial directions, and must be kept out of Check.
The EMPRESS is the compound of Rook, Bishop, and Unicorn.
Emperors and Empresses start side by side on Tunnel files g and f, on the same files. The names reflect their being an enhanced King and Queen.
The QUEEN is the compound of Rook and Bishop. Queens start on Tunnel files f and g, but on a different rank from the Emperor and Empress, surrounded by pieces with the Unicorn move that they lack. The name is inherited from 2d Chess.
The DUCHESS is the compound of Rook and Unicorn. Duchesses start on Tunnel file k, surrounded by pieces with the Bishop move that they lack. Its name refers to being akin to the Queen, but with a lesser secondary component.
The GOVERNOR is the compound of Bishop and Unicorn, and the components' different bindings make the piece unbound. Governors start on Tunnel file j, surrounded by pieces with the Rook move that they lack. Its name is a religious title of British monarchs following the Reformation.
Obliquely enhanced Rooks
The MARSHAL is the compound of Rook and Knight. Marshals start on Frame file m, diagonally adjacent to Governors. Its name means the rank of officer who originally organised horses, and contains the Japanese words for horse (ma) and chariot (sha).
The NINSHAL is the compound of Rook and Ninja. Ninshals start on Wall file i, beside Governors. Its name is Marshal substituting the Nin of Ninja for its root, the Mar of Mare, and I would be interested if anyone knows what the Japanese syllable nin means.
The SENVASSER is the compound of Rook and Sexton. Senvassers start on Wall file n, directly below Governors. Its name is Canvasser (Rook+Camel) substituting the Se of Sexton for the Ca of Camel.
Obliquely enhanced Bishops
The CARDINAL is the compound of Bishop and Knight. Cardinals start on Frame file p, diagonally adjacent to Duchesses. Its name means a Catholic episcopal rank.
The NIRDINAL is the compound of Bishop and Ninja. Nirdinals start on Wall file l, beside Duchesses. Its name is Cardinal substituting the Nin of Ninja for the Ca of Cavalry.
The SELIPH is the compound of Bishop and Sexton. Seliphs start on Wall file o, directly below Duchesses. Its name is Caliph (Bishop+Camel) substituting the Se of Sexton for the Ca of Camel, and like Caliphs Seliphs are colourbound.
Obliquely enhanced Unicorns
The CAVALCADE is the compound of Unicorn and Knight. Cavalcades start on Frame files a and d, diagonally adjacent to Queens. Its name means a parade of horses, as both components have equine names.
The NIVALCADE is the compound of Unicorn and Ninja. Nivalcades start on Wall files e and h, beside Queens. Its name is Cavalcade substituting the Nin of Ninja for the Ca of Cavalry.
The SEFILA is the compound of Unicorn and Sexton. Sefilas start on Wall files b and c, directly above Queens. Its name is Cafila (Unicorn+Camel, meaning a train of camels) substituting the Se of Sexton for the Ca of Camel, and like Cafilas and Governors the components' different bindings make the piece unbound.
All-oblique compounds
The SAMURAI is the compound of Knight and Ninja. Samurais start on Wall files b and c, directly above the Empress and Emperor respectively. Its name means a Japanese warrior of higher rank than a Ninja.
The CHURCHWARDEN is the compound of Knight and Sexton. Sextons start on Wall files e and h, beside the Empress and Emperor respectively. Its The name means a lay rank in the church higher than Sexton.
The OBERON is the compound of Ninja and Sexton. Oberons start on Frame files a and d, diagonally adjacent to the Empress and Emperor respectively. Its name, that of a Shakespeare character, is used here to stand for OBliquE baRON, from the SOLLS of its components being in a ratio of 2:3 like the radial Baron.
Front ranks
The COHEIR is a restricted version of the Heir, which is the forward-only form of the Baron and moves one step forward (away from its own camp) Bishopwise or Unicornwise. Whereas the Heir need only switch to a different file when it moves, the Coheir must switch to a different kind of file. It cannot switch between two Tunnel or two Wall files. Thus the b2 (White) Coheir can make its first move to a3, f3, or g3, but not c3 or e3; the f5 (Black) Coheir can move to a4, b4, c4, e4, or i4 but not g4, j4, or k4. This is a compromise between the full Heir and a divergent piece, and specific to Tunnelchess geometry. If the idea is popular I may make it the standard Tunnelchess front-rank piece. White Coheirs start throughout ranks 2 and u, Black ones throughout ranks 5 and r.

Rules

There is no initial double-step move, En Passant, or Castling.

Coheirs are promoted to a stronger capturable array piece on reaching a starting rank for such pieces (necessarily enemy ones).

Check, Checkmate, and Stalemate are as in FIDE Chess

Notes

The pieces can be represented by 4 distinguishable standard sets. Use set 1 King as Emperor, set 1 Queen as Empress, set 2 K/Q as Queen, set 3 K/Q as Nivalcade, set 4 K/Q as Sefila, set 2 Knight as Oberon, all Pawns as Coheirs, other set 1 pieces as their compounds with Unicorn, other set 2 pieces as their compounds with Knight, other set 3 pieces as compounds with Ninja, and other set 4 pieces as their compounds with Sexton.

Could the pieces of the two back-to-back ranks be rearranged as back and front ranks in a simple, non-besiege Ecutunnel on an 8-rank board? The answer is yes, as only 11 of the total of 32 pieces aside have a Rook move. Here is one possible array for such a variant:



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By Charles Gilman.
Web page created: 2006-05-11. Web page last updated: 2016-06-07