Community variant
NightMare
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: king (k), queen (q), rook (r), bishop (b), knight (n) and pawn (p).
- pawn (p) is a custom piece with Betza movement `N`.
- knight (n) is a custom piece with Betza movement `N`.
- bishop (b) is a custom piece with Betza movement `N`.
- rook (r) is a custom piece with Betza movement `N`.
- queen (q) is a custom piece with Betza movement `N`.
- The royal piece king (k) uses custom Betza movement `KN`.
Move rules
- Castling is not allowed.
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.
N
N
N
N
N
KN
move
capture
move or capture
initial only
hopper target
Fairy-Stockfish rules
[allknightnightmare:chess]
# 1. Disable standard castling because rooks can't slide orthogonally anymore
castling = false
# 2. Define custom piece slots using Betza notation for Knight movement (N)
customPiece1 = p:N
customPiece2 = n:N
customPiece3 = b:N
customPiece4 = r:N
customPiece5 = q:N
# 3. Map standard piece names to the custom knight-moving definitions
pawn = p
knight = n
bishop = b
rook = r
queen = q
# 4. Give the King Royal Centaur movement (King steps + Knight leaps)
king = k:KN
# 5. Starting FEN with castling rights turned off (-)
startFen = rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1