eXtreme Gammon is backgammon software written by Xavier Dufaure de Citres and released in 2009.[1] It is available for Microsoft Windows and mobile platforms.
According to the Financial Times, the program is the best backgammon player in the world, and the near-exclusive study tool for all serious backgammon players.
eXtreme Gammon provides a widely accepted benchmark number for players' skills called the Performance Rating or PR, with a lower number indicating a better rating. PR is the average equity lost per decision multiplied by 500. Only decisions not considered to be "obvious" are counted. [2]
| PR | Description | ELO equalivent | |
| 0.0-2.5 | World Champ | 2162-2240 | |
| 2.5-5.0 | World Class | 2077-2162 | |
| 5.0-7.5 | Expert | 1986-2077 | |
| 7.5-12.5 | Advanced | 1792-1986 | |
| 12.5-17.5 | Intermediate | 1593-1792 | |
| 17.5-22.5 | Casual Player | 1405-1593 | |
| 22.5-30.0 | Beginner | 1167-1405 | |
| 30.0 or more | Casual Player | 1167 or less |