Parity Chess

Parity Chess is chess on a 12x8 board with added Champions and FADs

The variant's name and design was inspired by my thought that about two thirds of the pieces (not counting pawns or kings) seemed relatively close in value to me, on a 12x8 board (all being well within a pawn's value of each other - see Notes section further below). Note that a Champion plus a K can force mate vs. lone K (on 12x8) in 37 moves maximum - Dr. H.G. Muller, citing endgame tables, which was another inspiration for this variant's design.

There is a preset available for play on Game Courier here.

Setup

Pieces

Parity Chess uses the 6 standard piece types in chess. Aside from that, this game uses two unorthodox piece types:

The Champion is a triple compound piece that moves like a wazir (one square orthogonally, that is by rank or file) or like an alfil (i.e. leaps 2 squares diagonally), or like a dabbabah (i.e. leaps 2 squares orthogonally).

The FAD is a triple compound piece that moves like a ferz (one square diagonally) or like an alfil (i.e. leaps 2 squares diagonally) or like a dabbabah (i.e. leaps 2 squares orthogonally).

Rules

The castling rules for Parity Chess are as follows: A king that has never moved, and is not in check, can 'leap' once a game, along the first rank, to any unattacked empty square between it and an unmoved rook, followed by said rook 'leaping' to the king's initial square so as to complete castling in one single move. It does not matter if any squares in between are occupied or under attack.

Threefold repetition of position or stalemate is a draw as in standard chess, and the 50 move rule is also in effect in Parity Chess (i.e. game drawn if no captures or pawn moves have been made before 50 consecutive moves by both sides). Pawns move as in chess, and can promote to any piece type included in the setup, except for a king.

Notes

I'd tentatively estimate the values for this 12x8 game as: P=1; N=3.06(or 3 approx.); B=3.75; FAD=Champion=3.86(or 3.75 approx.); R=5.5; Q=R+B+P=10.25; K's fighting value=2.67.

Regarding my estimate of a FAD's value on a 12x8 board, for example, I used FAD=Ferz+(Alfil+Dabbabah+P)+P [similar to how Q=R+B+P in chess], where I estimate Ferz=(K-P)/2, or 0.83, and Alfil=Dabbabah=(N-P)/4, or 0.515 each. I had also estimated Wazir=Ferz, and thus for me a Champion's estimated value is the same, by a similar calculation. However, a differing view on a FAD's value is that Dr. Muller, by way of his computer studies, concludes that a leaper that has a 'footprint' of 12 leaps ought to be worth about a rook in general (at least on 8x8, if not on many other board sizes as well). It may be worth noting that an Alfil+Dabbabah compound piece is thought by Dr. Muller to be worth somewhat less than 2 pawns on an 8x8 board.

Fast castling rules are used in this variant to try to facilitate king safety and development. Note that all the pawns are protected in the setup.

Last revised by Kevin Pacey.