Welcome

Welcome to the homepage dedicated to my expanding family of chess engines: Jazz, Sjaak and Leonidas!

Jazz is a fairly standard chess program. It currently has no opening book, and doesn't use an endgame database.

Sjaak is a much weaker chess program, but in addition to normal chess it can play a number of other games and chess variants.

Leonidas is intermediate between Jazz and Sjaak and was designed primarily to play Spartan Chess (see below), but it plays some more variants.

Supported variants (most of them can only be played by Sjaak, unless noted otherwise):

• Normal chess (all three programs can play this)
• Spartan chess, where black and white play with different armies and black has two kings (Sjaak and Leonidas can play this).
• Seirawan chess, where both sides start with an extra off-the-board piece that can be introduced later (Leonidas only).
• The Maharaja and the Sepoys, where white has only one piece (the Maharaja) (needs to be played as variant "fairy" in XBoard).
• Amazon chess, where the queen moves as an amazon (needs to be played as variant "fairy" inx XBoard).
• Knightmate, where the king moves as a knight and the knights move as a king.
• Berolina Chess, where pawns move one square diagonal and capture straight ahead.
• Shatranj, a historic precursor of modern chess.
• Capablanca Chess, a variant played on a 10x8 board with two extra pieces.
• Gothic Chess, the same as Capablanca Chess but with a different starting position.
• Fischer Random Chess and Capablanca Random Chess, which are like normal chess and normal Capablanca chess, but with a randomised starting position (Sjaak does not generate a starting position, however).
• Makruk, the Thai version of Chess.
• Pocket Knight, like normal chess, but players have an extra knight they can drop on the board.
• Grand Chess>, on a 10x10 board.
• Indian Grand Chess, or possibly Turkish Grand Chess. On a 10x10 with four extra pieces.
• Burmese chess, working but not tested fully.
• Courier chess, a medieval variant played on a 12x8 board.
• Chinese chess (Xiangqi), Black and white face eachother across the river that runs along the board, with their kings confined to their palaces.

The structure of the two programs is very similar, although Sjaak is more like a younger sibling than a descendant of Jazz.

Sjaak comes with a command-line tool for playing engine-engine matches called Sjef. This uses Sjaak as a referee so it can handle all variants that Sjaak knows about (in particular, it does not handle Seirawan chess, although I have a work-around in mind for that).

All programs are freely available (under the terms of the GNU General Public Licence) and can be used with any chess GUI that implements the UCI (Jazz) or XBoard/WinBoard (Jazz, Sjaak, Leonidas) protocols.