Archchess
Archchess — starting position
https://engine.moddable.games/play/?game=chess&variant=archchess
Archchess (Italian: Arcisacchiere) was invented by Dr. Francesco Piacenza and described in his book I camoeggiamenti degle Scacchi, published in Turin in 1683. It is played on a 10×10 board and adds two new piece types — the Centurion and the Decurion — plus two extra Pawns per side, to an otherwise standard chess army.
The rules described here are based on materials written by John Gollon (draft chapters of an unpublished second chess variant book), transmitted to Hans Bodlaender via Eric Greenwood in 1997.
The Board
10 files (a–j) × 10 ranks = 100 squares. Left corners at each player’s side are dark colored.
Starting Position
White (rank 1): Rook a1 · Knight b1 · Bishop c1 · Centurion d1 · King e1 · Queen f1 · Decurion g1 · Bishop h1 · Knight i1 · Rook j1
White pawns (rank 2): a2–j2 (10 pawns)
Black (rank 10): Rook a10 · Knight b10 · Bishop c10 · Centurion d10 · King e10 · Queen f10 · Decurion g10 · Bishop h10 · Knight i10 · Rook j10
Black pawns (rank 9): a9–j9 (10 pawns)
Pieces
| Piece | Movement |
|---|---|
| King | One square in any direction |
| Queen | Slides any distance orthogonally or diagonally |
| Rook | Slides any distance orthogonally |
| Bishop | Slides any distance diagonally |
| Knight | L-shaped leap |
| Pawn | One square forward; captures diagonally; double first step permitted (see en passant exception) |
| Centurion | Leaps exactly 2 squares horizontally, vertically, or diagonally (Dabbaba + Alfil), or leaps as a Knight. May jump over intervening pieces in all cases. |
| Decurion | Moves one square diagonally (= Fers) |
Promotion
Pawns reaching the last rank always promote to Queen. No other promotion choice is available.
Castling and the King’s Leap
Castling in Archchess is flexible: the Rook moves one or more squares toward the King’s original square, and the King moves one or more squares toward the Rook’s original square. As an alternative to castling, the King may make a King’s Leap: a jump of two squares straight forward or horizontally.
Conditions for either option: the King must not have moved previously; the castling Rook must not have moved; no square the King crosses is attacked by an opponent’s piece; the King does not land in check. Whether being in check prevents castling or the King’s Leap is not specified in the source.
En Passant Exception
Pawns may make a double first step, except when both of the following are simultaneously true: the pawn could be captured en passant by the standard rules, and the double step would block a check on the King. In that specific case, the double step is not permitted.
Special Rules
- Stalemate is a draw.
- Win by checkmate only.
- No bare King rule.
Attribution
Archchess (Arcisacchiere) by Francesco Piacenza, 1683. Rules documented at chessvariants.com/historic.dir/arch.html (Hans Bodlaender, from Gollon via Greenwood, 1997).