A highly enjoyable powerplay program that repays in-depth exploration.
Pros & Cons:
GNU Backgammon houses the all powerful GnuBG neural network engine in an ambitious freeware project which should delight all backgammon enthusiasts. Getting used to the slightly quaint ways* of this open-source program takes a while. However, the documentation is extensive and there's an excellent tutorial. On my system, the current build works fine in 2D but not in 3D.
There's a wealth of advanced options and capabilities. The "Analyse" features give you fascinating insights into the game and how the GnuBG engine is thinking (by getting a feel of the Temperature Map, for instance). The program logs moves to the right of the screen, so you can click back and forth to review the game. There's a "Hint" button" and a "Tutor" option that will give you GnuBG's expert feedback on your moves and mistakes.
If you find GnuBG's unfailing expertise as an opponent a bit too much of a good thing, you can adjust its playing level in various standard or user-defined ways. You can set the program to use the Crawford and Jackoby rules, and GNU Backgammon also supports Nack Ballard's challenging Nackgammon starting position, as well as the simplified hypergammon variation. GNU Backgammon will open and analyze game files saved in a wide variety of formats.
In short, GNU Backgammon is a highly enjoyable powerplay program that repays in-depth exploration - a must have for anyone with more than a passing interest in the game.
A portable version of GNU Backgammon has reached prerelease testing phase: the main game features seemed to work just fine on my system. The 2D interface benefits from a quick tweak (I switched the appearance to "Wood 1"). Highly recommended
*Hint: After selecting your "Options", you'll need to head straight back to the drop down "Settings" menu to click "Save settings".
GNU Backgammon was reviewed by Gizmos Freeware on based on version 20121023.