Guru Mahachaturanga

The first decision was how many of each piece to have. I stuck closely to original AOF2 numbers, but decided to have 2 each of Rook and Ferz. This made for better symmetry, as well as taking into account the fact that the Ferz returned to its original geometry is bound to half the board. I initially considered having only two Knights, which would make for 12 back-rank pieces. This suggested 12 files and so 12 Pawns and, hence my "in the modern sense" qualification above, an array in the style of Grande Acedrex. This fits the Guru's long leaps well but makes for rather a weak army, so I decided to retain a full AOF twice-FIDE (and twice-Chaturanga) quota of Knights and Pawns. As I added these between the GA-inspired ranks, in such a way as to start with all Pawns protected, each player's Elephants all started on their back rank, covering between them the player's odd ranks. I then threw in a few extra special moves to make pieces more mobile, of which the Elephant Charge (see rules section) is relevant only after promotion. For the variant name I settled on the name of the ancient game, prefixed with the Indian prefix for large and before that the name of the distinctive piece: GURU MAHACHATURANGA (GM4ranga).

For the Guru I decided on the ship image from my larger Wildeurasian variants. It may seem incongruous but it could perhaps be seen as a pun on leadership and worship. Its sail illustrates triangulation as it does for the Alibaba, and it has the advantage of being available in colour. This inspired me to add a 4-player subvariant, GURU MAHACHATURAJI (GM4raji), ending with the name of the ancient game's 4 player form. Note that the Chaturaji page somewhat confusingly uses the ship image for the Elephant. As my two variants would have the same first 14 letters I decided to use the same page and therefore a board the same size and shape as with 2 players. As this made for a greater piece density I reduced Knights and Pawns aside back to FIDE/Chaturanga numbers. Each player would have their King in the corner. Initially I considered having just one Ferz aside, diagonally adjacent to the King, and orthogonally surrounded by Elephants covering between them the opposite-colour squares to those covered by the Ferz. This would have made each Ferz vulnerable to the opposite-army Ferz and neighbouring-army Elephants, and Elephants to neighbouring-army Ferzes and opposite-army Elephants. As it would make the Elephant Charge an immediate possibility, though, I eventually decided instead to retain two opposite-binding Ferzes and divide the Elephants between their bindings in such a way as to postpone Elephant Charges until promotion as per GM4ranga.

Setup

The first decision was how many of each piece to have. I stuck closely to original AOF2 numbers, but decided to have 2 each of Rook and Ferz. This made for better symmetry, as well as taking into account the fact that the Ferz returned to its original geometry is bound to half the board. I initially considered having only two Knights, which would make for 12 back-rank pieces. This suggested 12 files and so 12 Pawns and, hence my "in the modern sense" qualification above, an array in the style of Grande Acedrex. This fits the Guru's long leaps well but makes for rather a weak army, so I decided to retain a full AOF twice-FIDE (and twice-Chaturanga) quota of Knights and Pawns. As I added these between the GA-inspired ranks, in such a way as to start with all Pawns protected, each player's Elephants all started on their back rank, covering between them the player's odd ranks. I then threw in a few extra special moves to make pieces more mobile, of which the Elephant Charge (see rules section) is relevant only after promotion. For the variant name I settled on the name of the ancient game, prefixed with the Indian prefix for large and before that the name of the distinctive piece: GURU MAHACHATURANGA (GM4ranga).

All the original images that I used were available in colour. This inspired me to add a 4-player subvariant, GURU MAHACHATURAJI (GM4raji), ending with the name of the ancient game's 4 player form. Note that the Chaturaji page somewhat confusingly uses the ship image for the Elephant. As my two variants would have the same first 14 letters I decided to use the same page and therefore a board the same size and shape as with 2 players. As this made for a greater piece density I reduced Knights and Pawns aside back to FIDE/Chaturanga numbers. Each player would have their King in the corner. Initially I considered having just one Ferz aside, diagonally adjacent to the King, and orthogonally surrounded by Elephants covering between them the opposite-colour squares to those covered by the Ferz. This would have made each Ferz vulnerable to the opposite-army Ferz and neighbouring-army Elephants, and Elephants to neighbouring-army Ferzes and opposite-army Elephants. As it would make the Elephant Charge an immediate possibility, though, I eventually decided instead to retain two opposite-binding Ferzes and divide the Elephants between their bindings in such a way as to postpone Elephant Charges until promotion as per GM4ranga. Guru Mahachaturanga

This layout can also be used for a 2d game between two identical or different modified AOF4 armies, and substitutions are noted.

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Guru Mahachaturaji

This layout is not recommended for AOF4-army substitutions, as it cannot replicate the promotion-by-Checkmate feature.

Pieces

	The KING moves one step along any of the 4 orthogonals and 4 diagonals. It must be kept out of Check. There is 1 King aside.
	The ROOK moves any distance through empty intermediate cells in any of the 4 orthogonal directions. There are 2 Rooks aside.
	The KNIGHT makes 2:1 leaps. It can move 2 ranks and 1 file or 2 files and 1 rank. On a 2d board a Knight cannot return to a cell in an odd number of moves. There are 4 Knights aside in GM4ranga and 2 in GM4raji.
	The ELEPHANT moves exactly two steps along any diagonal. The intermediate cell may be empty or occupied. Each Elephant is bound to one in eight squares. There are 4 Elephants aside, 2 covering subsets of each Ferz binding. Each foursome is bound collectively to alternate parallel orthogonals, in GM4ranga the players' odd ranks. Each Elephant is a threat, and vulnerable, to one Ferz of each enemy army and, in GM4raji, one neighbouring-army (but no opposite-army) Elephant. AOF4 armies substitute Bishops, except the Islamic one which substitutes Camels.
	The FERZ moves one step along any diagonal. It is bound to half a 2d board, and as it always moves from an odd to an even rank or vice versa it cannot return to a cell in an odd number of moves. There are two Ferzes aside, one for the paler and one for the darker squares. Each Ferz is a threat, and vulnerable, to each enemy's same-binding Ferz and each enemy's two Elephants bound to subsets of its binding. AOF4 armies substitute the relevant army's 2d Bishop compound.
	The GURU is a triangulating leaper (like the Gnu - see my piece article Man and Beast 03: From Ungulates Outward). Its components are the 4:1 Giraffe and 5:3 Gimel. It can move 4 ranks and 1 file, 4 files and 1 rank, 5 ranks and 3 files, or 5 files and 3 ranks. There is one Guru aside. AOF4 armies substitute a Prince.
	The PAWN, when not capturing, moves one step orthogonally toward the enemy camp in GM4ranga, or the nearest all-enemy edge of the board in GM4raji. When capturing they move one step along either of the two diagonals having that orthogonal as a component. This prevents an unpromoted Pawn in GM4raji reaching or crossing the long diagonal on which its King starts. There are 16 Pawns aside.

Rules

Initial double-step Pawn moves are restricted to 2-player variants, and within them to Pawns starting on the third rank. These can be captured En Passant by upromoted enemy Pawns regardless of where the latter start.

Castling in GM4Raji is identical to FIDE Kingside Castling. Castling in 2-player variants differs in that the King moves three steps instead of two. It is unlikely to be useful as often as in FIDE Chess, but it is there just in case.

A Pawn is promotable once it has made 5 or more moves, unless it can but does not make a double-step move, in which case the minimum is 6. On the far edge promotion is compulsory, otherwise it is optional. In 2-player variants promotion is to whichever piece type starts at the ends of the file, except that the King file is treated as a second Guru file. GM4raji treats the Pawn's noncapturing line as a GM4ranga file regardless of the 4-player array, so that e.g. a Pawn reaching a corner square must be promoted to a Rook. A Pawn promoted once cannot then be promoted further, so it may be worth delaying promotion in the hope that capturing as a Pawn will led to promotion to a better piece - a Rook rather than a Knight or a Guru rather than a Ferz - or to one more useful in conjunction with existing pieces.

A player who has promoted Pawns to Elephants on bindings where they had no array Elephants can carry out an Elephant Charge. This comprises two or more moves, capturing or noncapturing, in place of a single move. Each move must be a leap over one of their Elephants with another and none may start or end with any King in Check. This feature does not apply to variants substituting Bishops or Camels.

An Enlightened Move is an additional move available to a non-Pawn that is its own usual move away from (and notionally granted by) the same player's Guru. It may make any noncapturing and noncastling move of the same length from the Guru to a different square. In the Rook's case there must be no piece between either it or its destination and the Guru. Note that the "same length" rule means that a piece making an Enlightened move starts and ends the move on the same colour square - a King cannot move from a square adjoining a Guru orthogonally to one doing so diagonally, or vice versa. This feature does not apply to variants substituting Princes.

An Elephant Charge and an Enlightened Move cannot be mixed in the same move. If a Elephant leaps two others as part of an Enlightened Move it is not considered an Elephant Charge, and may be used to get a King out of, or put an enemy King in, Check - but not to capture. There is never a choice between the two by the same route as the Guru's presence blocks the Charge and its absence prevents the Enlightened Move.

Check, Checkmate, and Stalemate in 2-player variants are as normal. In GM4raji a player is Checkmated when their King is threatened by the player about to move. That player's pieces are removed from the game and play proceeds with the Checkmating player. The first player Checkmated loses and the player giving the third Checkmate wins.