Irish is the ancestor of Backgammon. The board and moves are extremely similar. One change is the current "doubles" rule. There is also no re-roll on a doubles throw. Other than that, the rules are fairly the same. Players move their pieces from their starting points around the board toward their home point. In relation to their positions facing the board, each player moves counter-clockwise around the board toward the opponent's base point. The initial placement of the fifteen game pieces is illustrated in the diagram below:
The game begins with each player rolling one die. The higher throw moves first. The play proceeds pretty much like modern Backgammon.
The dice are thrown, and the pieces are moved around the board to the base. Each die is taken as a separate move, although the same piece may make both moves. No piece may land on a point occupied by two opponent's pieces. If a piece, using the number from one of the dice, lands on a point with only one opponent's piece, that piece is removed from the board. The opponent can no longer play until his piece re-enters the board. The piece re-enters via a roll that allows a legal move to a point in the player's base. In the event all the points are occupied by two or more opponent's pieces, both players roll two dice. The one with the higher total chooses one piece to remove from the board, which must then re-enter the board as described above.
A player is required to move a piece if touched. If there are no spaces to land on, the turn is forfeited. Once all of a player's pieces are in the opponent's base, the player may begin casting pieces off. An exact roll isn't required to cast off.