In this article I will design an unorthodox chessboard I call Irregular Quadrangle Chess, and formulate appropriate chess rules.
The chessboard with initial arrangement of pieces is illustrated in the diagram on the right. It comprises 96 shaded quadrangles. Each player has nine pieces and eleven pawns. The files are a,b,c,d,e,f,g,h,i on one side and j,k,l,m,n,o,p,q,r on the other side. The pawn, like the pawn of orthodox chess, moves forwards from one shaded quadrangle to the next shaded quadrangle.
Example: white pawn on c3 can move to the next shaded quadrangle c4.
Also, when the pawn reaches a quadrangle near the frontier line (L), he can either change direction and move forward along another file toward the side (C) for promotion (for white) and the side (A) for black, or he may continue moving on the same file.
Example: If white pawn is on the quadrangle b4, then on the next move, he can either continue on the file b or take the file i and move to i5 (or p5). Also, when the pawn reaches the sides (B) or (D) he can change direction and move along another file towards the side (C) for white, resp the side (A) for black.
Example: if white pawn is on g5, then on the next move he can move to p6, then p7 then p8 and be promoted. The prise en passant is as follows: Example: let's say that white pawn is on the quadrangle c4 and the black pawn is on the quadrangle r5, then if on the next move r5 moves to r4, then white pawn on c4 can capture it en passant and go to r5.
Also at the start of the game, the pawn can optionally move two shaded quadrangles at a time.
The Castlings are done like the 9x9 chess, and are symmetrical. Example: Ke1-g1 and Rj1-f1, Ke1-c1 and Ra1-d1.
Remark: To avoid confusion for recording chess games, we will simply adopt the following: up to the frontier (L) White pieces moves are recorded in terms of the files a,b,c,d,e,f,g,h,i,j. Once they are in the black field, their moves will be recorded in terms of the files j,k,l,m,n,o,p,q,r. This also will apply for black pieces when they reach the frontier line (L). Example: If white pawn is on the quadrangle b6 of the file b we prefer to record it as m6, because he is on the black fields. Finally, the game ends with mating the King.
Remark: No pawn or piece can move on the no shaded quadrangles. of the chessboard.
The particularity of this irregular Quadrangles chess is that it is a perspective chess, a sort of hyperbolic chess (because the pawn (optional), Bishop and Queen vertical diagonal moves describe a hyperbola path. Because of the pieces move only on the shaded quadrangles, this chess games is no longer than the usual 8x8 chess.