The Royal Game of Ur
When the dice are rolled, the player may move one of his remaining pieces. Pieces on the board may attack (land on) the pieces of the opponent, causing them to be taken off the board and back to their starting position. Pieces that successfully traverse the path over the board are removed from the game. The first player to get all his pieces through and off the board is the winner.
There are several options below to control the complexity of the game. These include the path on the board, optional functionality when landing on or passing over certain tiles, and leaving the board.
First choose the path across the board. The first one is the most complicated, and the last one is what I saw someone else had implemented. I suspect the first one was the official one, partly because the "Extra Turn" tile occurs every 4. The last one is the least likely to have been the official path through the board. A variant of this has the additional four initial squares with an exit on the same tile where the pieces start. This seems unlikely, as it only extends the play without introducing any further complexity.
Choose which colour goes first.
Choose the options associated with the different tiles. This is where the complexity arises. A very simple game for beginners could be to remove all these options.
Land on this tile and receive an additional turn. If you roll 4 repeatedly, you can traverse the entire board (full path); of course, the chance of doing this is (1/16)^6. Or 0.000006% (The Sumerians did like the number 6!)
Cross this tile and be promoted (piece is flipped over and has additional markings). This is required when playing the path(s) where you traverse tiles more than once. A promoted piece behaves exactly like other pieces, but a non-promoted piece may not attack one that is promoted.
Stack up to four of the same colour on this tile. Most of these simply let the player get on the board, but one is available for either player. Having only one piece on this tile may or may not be safe from attack, but two or more are always safe.
Stack up to four of either colour on this tile. It's possible to detain an opponent on this tile, as only the top piece may move.
A promoted piece on this tile is safe from any attack.
Exact Number Exit
Require the exact number for leaving the board.
Captured pieces retain their status. A promoted piece when captured and sent off the board to the starting row will continue as a promoted piece when it enters the board again.