This page is written by the game's inventor, Daniel Zacharias. This game is a favorite of its inventor.

Expanded Chess

This is intended to be a logical expansion of chess to a 10x10 board.

It adds two well known pieces, and a new one that is closely related.

Setup

Pieces

The Pawn, King, Queen, Bishop, Knight, and Rook all have their familiar moves, including the pawn's initial double step and en passant.

The Gryphon makes a single diagonal step and then slides outward as a rook.

The Zebra jumps to the squares one diagonal step outward from those reachable by the Knight. It complements the Knight as the Gryphon complements the Rook.

The Osprey is a diagonal Gryphon. It jumps to the second square on the same rank or file, and then slides outward as a bishop. It complements the Bishop.

Rules

The rules are the same as chess, with the following exceptions.

Promotion

A pawn may promote on either the 8th, 9th, or 10th rank. Promote on the 8th and 9th ranks is optional. The choice of which piece to promote to varies with each rank.

Upon reaching the 8th rank, a pawn may promote to a Knight, Zebra, Bishop, or Osprey.
Upon reaching the 9th rank, a pawn may promote to a Rook or Gryphon.
Upon reaching the 10th rank, a pawn must promote to a Queen.

Castling

The King and Rook may castle. When castling, the King moves three squares towards the Rook, and the Rook moves to the last square passed over by the King. To castle, the following conditions must be met.

Every square between the King and Rook must be vacant
The King must not be in check
None of squares between the King and Rook may be attacked by a hostile piece
Neither the King nor Rook may have moved yet

Notes

This game originally only added the Gryphon and Osprey. It took longer for me to realize that the Zebra belonged too.

The promotion rules are intended to provide interesting options. I don't know how well they work.

I wasn't sure whether or not to allow castling, but I think it could be useful.

Expanded Chess can be played through Game Courier with this preset.

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Daniel Zacharias.

Last revised by Daniel Zacharias.

Web page created: 2017-01-19. Web page last updated: 2022-12-05

Comments

Expanded Chess. An attempt at a logical expansion of Chess to a 10x10 board.

🔔Notification on Wed, May 22 07:38 PM EDT:

The author, Daniel Zacharias, has updated this page.

H. G. Muller wrote on Sat, Sep 16, 2023 12:59 AM EDT in reply to NeodymiumPhyte from Fri Sep 15 11:29 PM:

Short castling seems to break the interactive diagram.

It seems to work for me. What exactly happens that you describe as 'break'?

NeodymiumPhyte wrote on Fri, Sep 15, 2023 11:29 PM EDT:

💡📝Daniel Zacharias wrote on Fri, Feb 10, 2023 09:08 PM EST in reply to David Paulowich from 01:59 PM:

I value thematic consistency, which is the only reason I added Zebras at all. Maybe I go too far with it at times. I do think they serve a functional role too by protecting the edge pawns. An Alfil-Zebra might be an interesting piece, but I wouldn't use it here because that would break the theme, unless the knights were made FN. I also don't want to have only very strong pieces; there are plenty of those already. I used zebras for aesthetic reasons; whether that choice makes for the best game, I cannot say.

H. G. Muller wrote on Fri, Feb 10, 2023 04:07 PM EST in reply to David Paulowich from 01:59 PM:

The AZ is a quite strong piece. It does not have mating potential, but is powerful enough to drive a bare King into a corner on boards up to 9x9. So it can pretty much checkmate in combination with anything. Even with an Alfil.