GNU Backgammon is Free Software and is a part of the GNU Project. You may download it for free. For more information see the GNU General Public License. But be aware that GNU Backgammon is not public domain software or shareware as you perhaps know from MS Windows.GNU Backgammon is free as in freedom , i.e. all the source code is there for you to inspect, change or distribute as long as you keep said license.