Community variant
Promotion
Every piece including kings promotes to its upgraded form when reaching the backrank.
This is a user-catalogued casual variant. Technical details such as board size,
FEN, pieces, and hand rules are defined in the Fairy-Stockfish
variants.ini block below.
Generated rule overview
This variant inherits its base rules from `chess` and overrides the settings shown below.
Board and setup
Pieces and movement
- The piece set used on the board is: custom piece 6 (k), queen (q), rook (r), bishop (b), knight (n) and pawn (p).
- custom piece 1 (z) is a custom piece with Betza movement `B`.
- custom piece 2 (y) is a custom piece with Betza movement `R`.
- custom piece 3 (o) is a custom piece with Betza movement `RB`.
- custom piece 4 (a) is a custom piece with Betza movement `QN`.
- custom piece 5 (j) is a custom piece with Betza movement `KN`.
- custom piece 6 (k) is a custom piece with Betza movement `K`.
- custom piece 7 (c) is a custom piece with Betza movement `N`.
Move rules
- Castling is allowed.
Promotion
- The pieces that can promote are: knight (n), bishop (b), pawn (p), rook (r), queen (q) and custom piece 6 (k).
- Promotion choices are both sides: no pieces.
- Fixed promotion mappings: n promotes to y, b promotes to y, p promotes to z, r promotes to o, q promotes to a and k promotes to j.
- Piece promotion is mandatory where promotion is legal.
Winning and losing
- An extinction rule is active: reaching 64 remaining piece(s) jk causes a loss for the side to move.
Piece movement
These diagrams show custom pieces and known Fairy-Stockfish built-in fairy pieces from White's perspective on a compact preview board. Some special moves, especially hoppers and game-state-dependent moves, can still depend on blockers or game state.
B
R
RB
QN
KN
K
N
move
capture
move or capture
initial only
hopper target
Fairy-Stockfish rules
[promotion:chess]
customPiece1 = z:B
customPiece2 = y:R
customPiece3 = o:RB
customPiece4 = a:QN
customPiece5 = j:KN
customPiece6 = k:K
customPiece7 = c:N
extinctionValue = loss
extinctionPieceTypes = jk
extinctionPseudoRoyal = true
extinctionPieceCount = 64
mandatoryPiecePromotion = true
promotedPieceType = n:y b:y p:z r:o q:a k:j
promotionPieceTypes = -
castling = true
castlingRank = 1
castlingKingPiece = k
castlingRookPieces = r