Introduction

In Seirawan Chess (S-chess) the rules are the same as in orthodox chess, except that two pieces, the Elephant and the Hawk, are placed in the reserve. The Elephant (Chancellor) combines the powers of a Rook and a Knight. It is comparable in strength to the Queen. The Hawk (Cardinal) combines the powers of a Bishop and a Knight. It is somewhat weaker than a Queen. These pieces are known from Capablanca's Chess.

Whenever a piece leaves its initial square, one of the extra pieces can immediately be introduced to the vacant square. So this is a double move, comparable to castling. Should a player refrain from inserting his extra pieces at these occasions, then he has forfeited his chance of introducing them. When castling, one of the extra pieces can be placed on either of the squares left vacant, namely the corner square, or the e1/e8 square.

Note! When making a move that allows you to introduce a piece, but you still want to keep it in the reserve, then you must acknowledge this by lifting and dropping the external piece. Pawns can, additonally, promote to Elephant or Hawk.

Alternative variant

I introduce an alternative variant (program SeirawanChess-alternative.zrf) where the external pieces must, in the first moves, be placed on the file on which the player intends to introduce the pieces. If, for instance, the player places the external piece behind his own queen, then the piece is automatically introduced on the queen's initial square when the queen moves away. If a piece is placed behind the king then it is also introduced at castling. The same is true if the external piece is placed behind the rook. Should a piece on the initial position be captured (exchanged), then the player has forfeited his right to introduce an external piece placed behind it.

Note! The player is not allowed to position one piece on the king file and one on the rook file. This rule will prevent him from introducing two pieces simultaneously at castling. This variant solves the problem of the bishop fianchetto mentioned above. This method of introducing external pieces is probably ideal while the strategical situation is clarified before play begins. This variant of Seirawan Chess is the same as a variant of Pioneer Chess (see "Pioneer Chess").