Jetan

Jetan, also known as Martian Chess, is a chess variant with unclear rules. It was created 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 described in Chapter 2 and in the Appendix of the book.

Jetan is played on a black and orange checkered board of 10 rows by 10 columns, with orange pieces on the "north" side and black pieces on the "south".

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 Chief at left center, the Princess 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. The complete arrangement of each side follows:

Throughout the Internet there is seemingly much confusion regarding the play of this chess variant. The sole existing authority on Jetan being Edgar Rice Burroughs, with the finalized version of the rules presented in the Appendix of The Chessmen of Mars. This article attempts to match it.

Panthans are limited to one step per move: forward, diagonally forward and sideways. Other pieces take two or three. These may change their direction of movement at each step in the course of a move, so long as this is in a direction permitted for that piece. Each must take the full number of steps specified for it. No piece can cross the same square of the board twice during the course of a move. The Princess and the Flier (Odwar), may jump over a piece that is in their path.

A capture is made when a piece lands on a square occupied by an opposing piece with its final step or jump; the Princess may not make such a move.

The pieces move as follows:

If it must, then an opposing piece in a [.] square would block the Padwar (at [O], which could not move to an [X] square in that direction. If not, then the Padwar could capture a piece at [.]. Presumably it may only capture once per turn.

In Burroughs's description, Jetan is won when either a Chief captures the opposing Chief, or when any piece captures the opposing Princess. 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.

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