Jetan is a game from Barsoom that somewhat resembles earthly chess. The game is played with twenty black pieces by one player, and twenty orange pieces by the other on a board of one hundred (100) alternating orange and black squares. It is typically arranged so that the black pieces are played from the south, and the orange in the north.
The pieces are laid out in the following order:
- In the first row (the row nearest the player), from left to right: Warrior, Padwar, Dwar, Flier/Odwar, Chief, Princess, Flier/Odwar, Dwar, Padwar, Warrior.
- In the second row, from left to right: Thoat, Panthan, Panthan, Panthan, Panthan, Panthan, Panthan, Panthan, Panthan, Thoat.
Warrior — Two spaces straight in any horizontal or vertical direction or combination. It is displayed with two feathers.
Padwar — A padwar moves two spaces diagonally in any direction or combination. It is displayed with two feathers.
Dwar — Three spaces straight in any direction or combination. It is displayed with three feathers.
Chief — Three spaces in any direction or combination: straight or diagonal or combinations of these. It is displayed with a diadem with ten jewels.
Princess — Moves as chief, but may additionally jump intervening pieces. Once during the game she may make one ten-space move called the escape. She may not move into a threatened square nor may she capture an opposing piece. She is displayed with a diadem with one jewel.
Thoat — Represents a mounted warrior. It moves two spaces, one straight and one diagonal in any direction, and is displayed with two feathers.
Panthan — One space, either straight or diagonally forward, or to the left or the right, but never backward. They are displayed with one feather.
A straight move is any move north, east, west, or south. A diagonal move is any move northeast, northwest, southeast, or southwest. A combination move is a sequence of moves in any direction allowed for a given piece so long as the piece does not cross the same square twice in the same move.
The first move is decided in whatever manner is agreed upon by the two players. After the first game, the winner decides who will have the first move in the next game.
The game is won when any piece captures an opposing Princess or when a Chief captures the opposing Chief. The game is a draw when any other piece captures the opposing Chief. The game is also a draw if both sides are each reduced to three pieces, of equal value, or less and the game isn't won within the next ten moves (five per side).
When gambling, stakes can be placed on entire games, on individual pieces (i.e. each piece is assigned a monetary value which must be surrendered to one's opponent upon its capture), or both.
The game is presumed to have to have originally represented a battle between the Black race of the south and the Yellow race of the north (thus the reason for the black pieces in the south and orange in the north).
There are several differences in the way jetan is played in the nation of Manator:
- The piece called "Flier" in the rest of Barsoom is called an "Odwar" in Manator and is displayed with five feathers.
- The game is sometimes played with human beings on a large field instead of on a board with carved pieces.
- During games with human 'pieces', squares are contested, not automatically taken. The manner of capturing a square is determined before the game and can be death of one of the 'pieces', fencing points scored, first blood, etc. Expulsion from the square also denotes a capture by the remaining 'piece'.