In Bolyar Chess, a historical variant native to Bulgaria, the goal is checkmate. The following pieces move as in classical chess: king, pawn, knight, rook, and general (which is the same as queen). The general only appears when a boat promotes (see below). Castling is "long" also on the king's wing (while the central board is 9 squares wide). Rules for 'en passant' capture are standard.

The following pieces use special movement rules. The bishop moves on the diagonals like a regular bishop, but it can also move one square forward, provided that this square is empty. The bolyar (which means "royal knight"), initially positioned on either side of the king, moves like a queen, but can only capture on the orthogonals (that is, capture is not allowed when moving diagonally). The boat, initially positioned on the extra corner squares, can move maximally two squares, orthogonally, diagonally, or like a knight. However, it can only capture when moving orthogonally (like a rook). Moreover, it cannot move in the backward directions, except when capturing orthogonally.

The Bulgarian boat is the most complicated of the pieces. Blue = both capture and movement. Green = only movement. Red = only capture.

 
Promotion rules

These differ much from regular chess. All pieces, except bolyar and general, always promote to bolyar when reaching the last rank. This is true also for the pawn and the bishop (which can also promote on the far side corner squares).

The knight has an additional promotion rule. Should it reach an enemy corner square it promotes to bolyar, and, as a bonus, boats are added to the home corner squares that happen to be empty.

The boat also has an additional promotion rule. Should it reach an enemy corner square it promotes to general, and, as a bonus, boats are added to the home corner squares that happen to be empty.

 
History

This variant has its roots in medieval Bulgaria. In modern times castling and 'en passant' were added. Bolyar (Bulyar) Chess was still played in the nineteenth century, but has since then fallen into oblivion. It is an imaginative game. 'Bolyar' is an old Bulgarian title of nobility.

 
References

http://bgchess.hit.bg/enstart.html