John Gollon, well known by chess variant enthousiasts for his book on chess variants, now unfortunately out of print, was working on a second book on chess variants. Also unfortunately, this second book was never published. Gollon has sent some materials from a draft of the book to Eric Greenwood (in 1976): the description given here is based on part of these writings by Gollon.
D. Pietro Carrera invented this chess variant in the 17th century. He wrote a long book on chess, called Il Gioco delgi Scacchi, and published it in 1617 in Miltello in Sicily. The variant was probably little played. The game was again mentioned by Ben Foster in his booklet on Chancellor Chess, and in a book from 1804 called An Introduction to the History and Study of Chess. Also, Murray mentions the game, but with a somewhat different (possibly wrong) startup position.
The game is interesting because it is one of the first, perhaps the first, variant to feature the Rook-and-knight and the Bishop-and-Knight combinations.
The game is played on a checkered board with 8 rows and 10 columns. The left corners at each players side are dark colored. The opening setup is as follows:
King e1; Queen f1; Champion b1; Centaur i1; Rook a1, j1; Knight c1, h1; Bishop d1, g1; Pawn a2, b2, c2, d2, e2, f2, g2, h2, i2, j2.
King e8; Queen f8; Champion b8; Centaur i8; Rook a8, j8; Knight c8, h8; Bishop d8, g8; Pawn a7, b7, c7, d7, e7, f7, g7, h7, i7, j7.
King, Queen, Rook, Knight, Bishop, and Pawn move as in orthodox chess, but there is no castling, and a somewhat different en passant rule (see below). The precise pawn promotion rules are unknown; it probably is best to play that a pawn may be promoted to queen, champion, or centaur to the choice of the owning player; or alternatingly only promote pawns to queens. (Minor promotion was probably unknown to Carrera.)
The champion has the combined moves of rook and knight. The centaur has the combined moves of bishop and knight.
Pawns may make an initial double step, but not if they could be taken en passant by the rules of orthodox chess and at the same time block a check. So, for instance, when there is a black pawn on c4 and white's king on e1 is in check from a bishop on a5, then white may not move a pawn from b2 to b4.
Stalemate is a draw; a player wins by mating the opponents king.