Ur is a two player game played on a game board "found in the Royal Tombs of Ur by Sir Leonard Woolley in the 1920s. The two boards date from the First Dynasty of Ur, before 2600 BCE, thus making the Royal Game of Ur probably the oldest set of board gaming equipment ever found."*
The two players (white and black) take turns rolling dice and moving all six of their pieces around the board along their path as shown below. The first player to advance all of their pieces all the way around and back off of the board wins.
There are four four-sided dice. Each die has two "1" sides represented with a white spot and two "0" sides without a spot. On your turn, roll the four dice, which will result in a number between zero and four. Pick one of your pieces and move it that many spaces forward along your path.
If your piece lands on an opponent's piece, remove the opponent's piece from the board and return it to its starting position. You may not move a piece which would land on one of your own pieces. You may also not move a piece that would land on a rosetta spot if an opponent's piece is already on that spot.
If your piece lands on one of the five rosetta spots, you take another turn.
A piece may only be moved off of the board on an exact roll of the dice. For example, if one of your pieces is on the final spot in your path (the rosetta at the end of the board), you can only move it off of the board if you roll a one.
If you roll the dice and have no legal moves, you pass your turn.
The Ur board and piece graphics used on games.wtanaka.com are derived from the CC-SA photo on wikipedia, copyright Zzztriple2000 and are relicensed here under the same license. Attribution can be made by linking to this page