Jetan

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For the unrelated Icehouse game, see Martian Chess.

The Chessmen of Mars by Edgar Rice Burroughs, McClurg, 1922

Jetan, also known as Martian Chess, is a strategy game for two players invented by Edgar Rice Burroughs as a game played on Barsoom, his fictional version of Mars. The game was introduced in The Chessmen of Mars, the fifth book in the Barsoom series. Its rules are provided in chapter 2 of the book and an appendix at the end of the book.

The game is said to represent an ancient war between the Yellow and Black races of Barsoom, and thus the game is played on a black and orange checkerboard of 10 rows by 10 columns, with orange pieces on the "north" side and black pieces on the "south." The board is traditionally oriented to these directions because Barsoom's Yellow and Black races inhabit its north and south polar regions, respectively.

Each player has the following playing pieces: one Chief, one Princess, two Fliers; two Dwars (Captains); two Padwars (Lieutenants); two Warriors; two Thoats (Mounted Warriors); and eight Panthans (Mercenaries). The Chief, Princess, Fliers, Dwars, Padwars and Warriors are positioned along the row closest to the player, with the Princess at left center, the Chief at right center, and the Fliers, Dwars, Padwars and Warriors arranged to flank each, with the Fliers innermost and the Warriors outermost. The Thoats and Panthans are positioned along the next row out from the player, with the Thoats flanking the Panthans.

Pieces can change their direction of movement during the course of a move, so long as the change is in a direction permitted for that piece. Each piece must move the full number of spaces specified for that piece. No piece can cross the same space twice during the course of a move.

The pieces move as follows:

Chief: three spaces vertically, horizontally, diagonally, or in any combination of these directions; cannot jump over other pieces.
Princess: three spaces vertically, horizontally, diagonally, or in any combination of these directions; may jump over other pieces but cannot take other pieces. May make one "escape" move during the game to any unoccupied space on the board.
Dwar: three spaces vertically, horizontally, or in any combination of these directions; cannot jump over other pieces.
Flier: three spaces diagonally, either in straight line or in a combination of diagonal directions; may jump over other pieces. Per Burroughs, in an older version of Jetan these pieces were called Odwars rather than Fliers.
Padwar: two spaces diagonally, either in a straight line or in a combination of diagonal directions; cannot jump over other pieces.
Warrior: two spaces vertically, horizontally, or in any combination of these directions; cannot jump over other pieces.
Thoat: two spaces, of which one is vertical or horizontal and the other one diagonal, in any direction; may jump over other pieces.
Panthan: one space vertically, horizontally, diagonally, or in any combination of these directions, so long as it is not backward (Burroughs' text does not clearly prohibit backward play, but test play indicates that permitting it makes the piece the most powerful in the game, in contrast to his intent that it be the weakest.)

Per Burroughs, the game is won by either taking the opponent's Chief with one's own Chief, or the opponent's Princess with any piece. The game is drawn if each player is reduced to three or fewer pieces of equal value and it is not won within the next ten moves, or if a Chief is taken by any piece other than a Chief. It having been demonstrated that these rules result in too many draws, a number of variants have been proposed to solve this flaw, the simplest being that the taking of a Chief by a piece other than a Chief merely retires the Chief, without ending the game.

Rule variations noted above are per Jean-Louis Cazaux's Jetan page at http://www.chessvariants.com/other.dir/jetan.html.

[edit] Trivia

Burroughs' Jetan inspired authors of later planetary romances to invent similar extra-terrestrial versions of chess fought with human beings. Instances of such homage include:

Lin Carter's Darza, from Renegade of Callisto, eighth volume in his Callisto series
Kenneth Bulmer's Jikaida, from A Life for Kregen, 19th volume in his Dray Prescot series