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Software Review: eXtreme Gammon

Some product reviews are hard to write. Do I like this product? Do I really like this product? Can I wholeheartedly recommend it, or do I have a few lingering reservations?

Fortunately, eXtreme Gammon (or ‘XG’ as it’s known in the backgammon world) presents no such problems. It’s the best backgammon software available, and if you’re a serious player (or aspire to be one) you have to have it. Period.

[Before I go on and tell you what it does and why you have to have it, I’m going to insert a disclaimer. In today’s commercial world ruled by the internet, a lot happens behind the scenes and under the table. Is a review honest, or is it driven by silent payments and link exchanges that you the reader know nothing about? I have no commercial relationship with eXtreme Gammon. I own and use four copies on four machines, all of which I paid for. What follows is my personal opinion, and nothing else.]

eXtreme Gammon is a fourth-generation neural net backgammon program. The first generation was a program called ‘TD-Gammon’, developed by Dr. Gerry Tesauro at the IBM research laboratories in White Plains back in the late 1980s. The project was designed to test the effectiveness of neural-net technology in various real world applications. Neural nets turned out not to be suitable for some applications, but they were fabulously successful when applied to backgammon.

IBM had no interest in marketing TD-Gammon, but in 1994 Frederick Dahl created Jellyfish, a second-generation neural net. Jellyfish was similar in playing strength to TD-Gammon, but added plenty of useful features to make it a successful commercial product. In 1998 Jellyfish was superceded by Olivier Egger’s Snowie, which featured another jump in playing strength and many additional user features. Snowie ruled the roost for 11 years but in 2009 the first version of XG was released with yet another big jump in playing strength as well as huge improvements in speed and user features. XG version 2 followed a few years later, and version 3 is rumored to be nearing release.

All right, that’s enough of a history lesson. Now let’s look at some of the features that make XG an essential tool for a backgammon player.

Price. The top-of-the-line version of Jellyfish sold for $250 in 1995. The full-featured version of Snowie came in at a cool $380, and backgammon pros were happy to pay that 15 years ago. In fact, we thought it was a bargain. But one installation of XG costs only $60, and you can buy two installations for $90! It’s a little like going out to buy the latest Lexus LS and discovering that Lexus has cut the price to $10k. Frankly, I’d buy XG if it cost 10 times what it does.

Analysis Levels. You can enter a position into XG and choose the level of analysis you want. In most situations, you’ll just pick the highest level (called XGR++) and let XG do its thing. If you’re suspicious of the result or just want the best possible answer, you can force XG to do a rollout of any length. (1296 trials is the default.) In 99% of the cases, the rollout will confirm the analysis, but once in a while the rollout will say a different play is better.

Playing Strength. When you practice against XG, you can set its playing strength to any of 11 different levels. The lower levels allow beginners to create a competitive situation for practice. If you’re using XG to improve your own game, then you should use one of the higher levels (Champion through XGR++). Which one you use depends on the speed of your processor. At any of the higher levels, XG is considerably stronger than the best human players.

Does XG play perfectly? No. XG plays extremely well, and its occasional mistakes in normal-type positions will usually be caught by a rollout analysis. There are certain types of positions where XG makes systematic mistakes: massive backgames and certain kinds of containment positions. These positions arise very rarely in normal play, so XG has never had a chance to train itself in these situations. Supposedly XG version 3 is being developed and refined to address these problems.

Speed. When playing against XG on an i7 quad-core machine, all the levels are virtually instantaneous except for XGR++. Even on slower laptops, the XGR+ level plays at an acceptable speed (a few seconds per move). On an older or severely underpowered machine, you might have to drop down to ‘Champion’ level to play comfortably.

Extra Features. There are almost too many to mention, but here are a few of my favorites. You can choose colors, board, and checker styles from a very large palette. You can import recorded matches from recent tournaments directly into XG and study the games of the best players. You can very easily transcribe matches that exist only in video or text form. You can go through an entire match and mark moves you want XG to roll out, then batch the entire group to run overnight.

Does XG Run on a MAC? XG is a Windows product, so it won’t run unaided on a MAC. There are emulator programs which create a Windows environment in a separate window on a MAC. XG’s web site mentions the ‘Parallel Desktop 4.0’ package as one such emulator. Note however that eXtreme Gammon does not claim to support such an arrangement, so if something goes wrong you’re presumably on your own.

How Good is XG Mobile? What I’ve described so far is the full-featured eXtreme Gammon running on Windows desktops or laptops. A top-notch backgammon neural net requires a lot of computing power, so the company created a lower-level version for Apple and Android phones, which you can download either from Apple’s App Store or Google Play. What you’ll download will be a free version. You can upgrade to an enhanced version for a small fee.

I’ve only played a few games against the free version of XG Mobile, just enough to verify that it’s considerably weaker than the full-featured desktop version. I don’t know whether or not it’s better than other phone apps like ‘Backgammon NJ’. I also don’t know how much of an improvement the upgraded version is.

All in all, XG on a fast Windows desktop is a fantastic product. If you’re a serious player looking to improve, you must own eXtreme Gammon.


Posted: September 12, 2017 | In Backgammon Software

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