Shafran's Variant

Origin

Devised by Isaak Grigorevich Shafran in 1939 and refined through the 1950s in the Soviet Union, Shafran's hexagonal chess trades the tidy geometry of Glinski for a wide, stretched board that rewards long diagonals and armoured king wings. It is the only major hex variant to retain castling.

Board

An irregular hexagon of 70 cells in three colours, nine files wide (a through i) and ten oblique ranks tall. The board's rank lines bend 60° at the e-file, so the a-file spans ranks 1–6, the e-file spans all ten ranks, and the i-file spans ranks 5–10. The kings begin on e1 and e10, at the two points of the hexagon.

Starting Position

Each side has 18 pieces:

• 1 King · 1 Queen
• 2 Rooks · 3 Bishops · 2 Knights
• 9 Pawns (one per file, immediately in front of the back rank)

Back rank (from queen's flank to bishops' flank):

Rook — Knight — Bishop — Queen — King — Bishop — Knight — Bishop — Rook

White's back rank runs a1, b1, c1, d1, e1, f2, g3, h4, i5, so the queenside rook sits on a1 and the bishopside rook climbs the diagonal to i5. Black mirrors: rooks on a6 and i10, king on e10.

How Pieces Move

Rook, Bishop, Queen, Knight, King

Identical to Glinski's and McCooey's. Rooks slide the six orthogonal hex directions; bishops slide the six hex diagonals; the queen combines both; kings step one hex in any of twelve directions; knights leap the standard hex knight shape (twelve destinations).

Pawn

Pawns advance straight up their file toward the enemy back rank and capture one hex forward on either bishop-diagonal (one rank and one file at once).

Opening reach: on its first move a pawn may advance one, two, or three squares toward the middle of its file. Because file lengths differ, each pawn has its own cap: the d-, e-, and f-pawns may leap three squares; the b-, c-, g-, and h-pawns may double-step; the corner a- and i-pawns may only step one. All squares along the path must be empty.

Promotion: a pawn that reaches the last rank of its file promotes to Queen, Rook, Bishop, or Knight.

En passant: not tracked in this implementation.

Castling

Unique among the mainstream hex variants, Shafran's keeps castling. Castling is possible on either wing — queenside (toward the queen's rook) or bishopside (toward the king's rook) — and in two lengths — short or long.

• Short castle: the king moves two squares toward the rook; the rook jumps three squares past the king.
• Long castle: the king moves three squares; the rook jumps two squares past the king.

As in classical chess, castling requires that:

• the king and the involved rook have not previously moved;
• all squares between the king and rook are empty;
• the king is not in check, does not pass through an attacked square, and does not land on an attacked square.

Notation: O-O · bishopside short · O-O-O · bishopside long · O-O-Q · queenside short · O-O-O-Q · queenside long.

Winning, Drawing, and Check

Checkmate wins. Stalemate is a draw. Threefold repetition draws automatically. Both players may agree to a draw at any time.

Differences from Glinski's and McCooey's

• Board shape: irregular 70-cell hexagon, nine files wide and ten ranks tall — narrower than Glinski's 91-cell board.
• Back rank order: R N B Q K B N B R across nine cells — an extra bishop on the king wing.
• Opening pawns: may leap up to three squares on the first move, capped per file so central pawns reach the middle in one bound.
• Castling: allowed — four flavours (queenside/bishopside × short/long).
• Pawn captures: bishop-diagonals (one hex forward on a diagonal), matching McCooey rather than Glinski's orthogonal flanks.