We’re excited to announce a major new addition to PlayStrategy.org: backgammon analysis and bot play!

Whether you’re completely new to backgammon, an experienced tournament player, or somewhere in between, you can now play against bots at different levels or challenge another user, and then dive into an analysis of your game to see exactly how well you played!

What is GNUBG?

GNU Backgammon (GNUBG) is to backgammon roughly what Stockfish is to chess: a free, open-source engine that plays at world-class strength and can tell you precisely where your game went wrong. It has been the analysis standard in the backgammon community for years, and it now powers both our bots and our analysis pages.

Want to test yourself against a computer opponent? You can now challenge our backgammon bots, from gnubg-level1 through gnubg-level8.

Understand Your Real Playing Strength

After your game, PlayStrategy automatically analyses it with the GNUBG engine and gives you much more than just a win or loss.

The analysis page is packed with useful information, including:

• Best move suggestions — see what the computer thinks you should have played.
• Win percentages — understand how your decisions changed your chances of winning.
• Performance Rating (PR) — get an indication of the quality of your play.
• Error information — see where you gave away equity and where your biggest mistakes happened.
• Luck analysis — find out whether you were genuinely playing well, or whether the dice were particularly kind or cruel.

The goal is to help you understand why you won or lost, not simply tell you the result.

What Does Your PR Mean?

PlayStrategy displays Performance Rating (PR) on the site. PR is calculated as half of the Error Rate (ER) from GNUBG analysis, so the playing-strength bands translate to:

PR -> Playing Level

Under 2.5 -> Super Grandmaster

2.5–5 -> World Class

5–7.5 -> Expert

7.5–12.5 -> Advanced

12.5–17.5 -> Intermediate

17.5–22.5 -> Casual

 22.5+ -> Beginner

For the moment, analysis applies to Backgammon and Nackgammon, single point games only. Support for multi-point matches and cube play is coming as part of further changes and refactoring to the backgammon system. You can go back and analyse old games and find out if you really were unlucky!

The best way to improve at backgammon is to play, analyse, learn and play again.

Can you beat the bots? Can you reach Expert? World Class? Maybe even Super Grandmaster?

Challenge the bots and see how good you really are.