Rules - Ahemmetter/royal-game-of-ur GitHub Wiki

The rules for the Royal Game of Ur are fairly straight-forward. Variations exist, but in this program only one ruleset so far is implemented: the British Museum ruleset.

The game board consists of 20 colored squares, arranged three horizontal rows. Each player initially has 7 stones in his color (black or white).

Starting board

Players take turns throwing marked tetrahedrons (equivalent to throwing dice with changed probability distribution). The possible outcomes are 0, 1, 2, 3 or 4, where 2 is the most probable. Each player moves any stone the designated number of fields along a certain path with the goal of reaching the end and "freeing" the stone. The game ends when one player has managed to get all his 7 stones out of the game before the other player.

A complication is added by two additional rules:

  1. The players can kick each other back to the start. For this a stone must hop to a field where a stone of another player is already sitting.
  2. The players can throw the dice again, if they land on a red square ("rosette") with their previous move. The red squares are spaced 4 fields apart. This means that the game can be efficiently traversed, if the players only throw 4s.