Computer Backgammon Programs
I've been getting a lot of questions about computer backgammon programs.
There are three programs worth the attention of serious players, Jellyfish, Snowie, and GNUBG. The first two were written respectively by Effect Software and Oasya (now called, I think, Snowie Group). GNUBG is part of the open-source GNU project.
As far as the strength of these backgammon programs, they are all pretty close. GNUBG is probably the strongest, then Snowie, then Jellyfish. Not so you'd notice.
The decision which one to get should be based on other factors; All three play an extremely strong game on the highest levels of play.
I own all three programs, although I am not that familiar with GNUBG. What is important to know is that Jellyfish and Snowie cost money, and GNUBG is free. Snowie can be bought here.
If you are looking for a summary of the game downloads available from online servers have a look at the backgammon downloads article on the site.
Snowie Backgammon Software
Snowie board game software during play
Just before we start I have a page that has an in depth descriptions of Snowie at my Snowie backgammon software page.
Snowie has three versions (called, I think, Player, Student, and Professional). The main differences between Snowie and Jellyfish are:
The player version of Snowie is not free. You can download a trial copy, but it will stop working after about two months. Then you either need to pay a registration fee, or order the CD-ROM version. The CD-ROM version is the same except that it has a database that makes some slightly better moves in the endgame. Not a significant difference.
The backgammon graphics on Snowie are more elaborate and you can read about the fetures in the Snowie product page. Frankly, I prefer Jellyfish.
The "rollout" features in Snowie are much better. For example, one of the most common reasons for doing a rollout is to verify which play or cube decision is better. Jellyfish requires you to set up each position separately and does not give a side-by-side comparison. Snowie allows you to just click on the position and possible moves you want and roll them all out. Also, Snowie will do much more effective rollouts considering ownership of the doubling cube. I think, but am not positive, that Snowie also calculates the value of gammons far more precisely in match play than Jellyfish does.
Snowie Professional is much more sophisticated than Jellyfish Analyzer. It costs $380. It allows you to import backgammon matches played elsewhere and analyze them. It will show you how well or badly you played, how lucky or unlucky you were, what cube decisions you made right or wrong. You have to save the text file of your moves from the match and run them through a conversion program in order to analyze the match.
Snowie is copy-protected. Jellyfish is not. For Snowie, you have to get a registration code from Oasya that you enter into your computer. This can be a bit annoying. I have on the site a guide to analyzing a game on snowie.
Jellyfish Tutor is available on floppy disk. Jellyfish Analyzer and all versions of Snowie are on CD-ROM only but now can be downloaded from the Snowie site as well (after paying of course).
Jellyfish Backgammon Software

Jellyfish Software in a game
Player - This plays against you, but it will not tell you why it's doing what it's doing. When it makes a play, it will not tell you what other plays it considered or how close the decision was. This version however is free.
You can download it for free.
Tutor - this adds the feature where you can get a list of the 2, or 3, or 5, or 8, best backgammon moves, and how good or bad each one is. You can also set Jellyfish to tell you when you make a play that is more than a certain amount worse than the best play. This version costs somewhere in the range of $100 - $110.
Analyzer - this adds the feature that you can "roll out" positions. If you really need to know the results of a position, the computer will simulate it hundreds or thousands of times. This version costs about $220 - $250. I would not recommend this version at this point in time. The rollout will not work on Jellyfish's highest playing level, and are not nearly as easy to use as Snowie or GNUBG's. When Jellyfish was written, Snowie and GNUBG did not exist, so this was an important function. Now, if you want to do rollouts, you'd use one of the other programs.
GNUBG Backgammon Software
Finally, there is GNUBG. GNUBG is free, and might be the strongest of the 3. If GNUBG had been written first, the others would not exist. At this point (2006), I don't know of anyone who would buy Snowie or Jellyfish when they can get GNUBG for free.
GNUBG backgammon Software in action
Having one of these programs is imperative for any serious or semi-serious backgammon player. The play level in backgammon has improved tremendously in the past 10 years, because of the availability of these programs. You do have to take it somewhat seriously though. You have to not just play, but also think about what the program is doing and why. Many cube decisions and checker plays have a lot to do with the match score. If you don't understand, for example, why the program plays very aggressively for a gammon in some situations and doesn't care about gammons in others, or why its doubling decisions are very different depending on match score, you'll miss a lot of the value.
One last important message about these programs. If you have the temptation to play online for money, these programs are a good way to gauge your actual ability. Take their ratings seriously. If you can play with a Snowie error rate in 5-point matches or longer of under 5.0, you can be competitive with the strongest online players. if you are in the 5-10 range, you probably won't get killed, but don't play for high stakes against strong players. If your Snowie error rate is over 10, stick to non-money play unless you really have a strong urge to gamble.
Backgammon Software - Should I get one?
Should you get one of these backgammon softwares? No. Definitely not. If you do and you start playing against it, your game will improve tremendously. Seriously, yes, yes, yes, get one. I learned a tremendous amount from playing against Jellyfish. You do have to take it somewhat seriously though. You have to not just play, but also think about what the program is doing and why. Many cube decisions and checker plays have a lot to do with the match score. If you don't understand, for example, why the program plays very aggressively for a gammon in some situations and doesn't care about gammons in others, or why its doubling decisions are very different depending on match score, you'll miss a lot of the value.
