A Cornucopia of 9x9 Corner variants

These variants have their origins in a 2-player variant with Kings in corners, possibly Diagonal Chess. If it rings any bells please remind me of its name. I wondered whether the principle of starting in corners could be applied to larger variants, on a not-that-much-larger board. Other variants influencing my thinking are my own Pass Variants, although unlike that page this one deals strictly with 2-player games using, or extrapolating from, European pieces. I could not face the complications of Chinese Rivers and Japanese "forward" definitions.

Orthogonal Draughts can also be played on a square board, 28 pieces aside giving a similar piece density (on available cells) to standard Draughts. As there is a face-to-face orthogonal Draughts played in Turkey, I distinguish my corner version by terming it British Orthogonal Draughts. See also notes.

Setup

Doubleback version

Doubleback Tutti Frutti version

Knighted-piece version

Ecumenical version

Wildebeest version

Courier version

Timur version

British Orthogonal Draughts

Pieces

Most pieces are the same as in face-to-face variants. Groups include:

	the FIDE Rook, Knight, Bishop, Queen (R+B compound), and King common to most variants;
	the "missing compounds" the Marshal (R+N) and Cardinal (B+N), added to the FIDEs for the B/C/C version, and the triple compound the Ace or Amazon (R+B+N) added to these for the double TF version;
	the pieces that are to the Knight what the Bishop and Queen are to the Rook, the Camel and the Gnu or Wildebeest, added to the FIDEs for the Wildebeest version;
	the further Camel compounds the Canvasser (R+C) and Caliph (B+C), added to all above but the Ace for the Ecumenical version;
	the Wazir, Ferz, Dabbaba, and Elephant of the Courier and/or Timur variants;
	the Picket of the Timur subvariant, which moves like the Bishop but always at least two steps, and the Giraffe of the same, which is a 4:1 leaper.

Pawns are a bit of an oddity. They move one step along either orthogonal toward the enemy camp except when they capture, which they do by making a single step along the diagonal directly toward the enemy camp. This combination of 2 noncapturing and 1 capturing directions gives a flavour of Berolina Chess. Alternatively the Yeoman, as I term the Pawn-substitute of that variant, can be substituted in subvariants of this lot, where it paradoxically restores the familiar 1 noncapturing and 2 capturing directions, and forking ability, that the Pawn itself has in the FIDE geometry. I do not recommend subvariants mixing the two. When either is on an enemy edge its orthogonal directions are reduced to the one toward the enemy King square, and its diagonal direction is the single one with that as a component.

OVERTAKING TWICE-PAWNS are the standard piece of British Orthogonal Draughts. These always move along either forward orthogonal, either one step to an empty square or two steps through a square occupied by an enemy (which is captured) to an empty square.

Rules

Pawns behind the front Pawn diagonal have an optional initial double noncapturing move, on either orthogonal. In subvariants using Yeomen, they have it on the diagonal toward the enemy camp. Promotion to a symmetric piece captured by the enemy is optional in the enemy camp and compulsory on the enemy King square.

In British Orthogonal Draughts, Twice-Pawns reaching the enemy camp are promoted to be able to move and capture along all four diagonals. Both pieces can make any number of successive capturing moves, but may make a noncapturing move only between two enemy moves.

Castling is as in FIDE Chess, with the King always moving two squares. I suspect that occasions when it is useful will be fewer than in face-to-face variants, but it is there just in case as the Rooks slotted fairly naturally into a position suiting this move.

Checkmate is as in FIDE Chess. In a modified version of the Diagonal Chess rule, players can also win by getting an unpromoted Pawn to the enemy King square when they have the full complement of symmetric pieces (and therefore nothing to promote it to). In British Orthogonal Draughts victory is by capturing the entire enemy army.

Notes

Piece density in standard Draughts appears superficially to be 3 in 8, but as half the squares of the board are inaccessible it is actually 3 in 4 accessible ones. Indeed standard Draughts can be transformed into an Orthogonal game on a diamond-shaped board:

Another illustration is in Hafts, which uses two modified Draughts sets (diagonal pieces Pawned only once to capture orthogonally) to give a 3 in 4 piece density over the entire 8x8 board.

Orthogonal Draughts on a square board should therefore aim for a piece density close to 3 in 4. This would mean armies of ideally 13-14 on a 6x6 board, 18 on a 7x7 board, 24 or an 8x8 board, 30 on a 9x9 board, and 37-38 on a 10x10 board. As you will see from the 9x9 array, however, there is an advantage to triangular numbers of pieces aside, and it is better to undercut than exceed the ideal piece-density number in order to give a gap similar to standard Draughts. This gives armies of 10 on a 6x6 board, 15 on a 7x7 board, 21 on an 8x8 board, 28 (as shown) on a 9x9 board, and 36 on a 10x10 board.

Orthogonal Draughts on a hex board best suits the Wellisch orientation. My Compact Hex Chess and Stelliform 6 player Chess pages include examples of this.

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By Charles Gilman.
Web page created: 2006-06-15. Web page last updated: 2016-04-05