Rybka currently tops all the computer chess rating lists. Since Rybka is pretty clearly stronger than the Deep Fritz program that defeated World Champion Vladimir Kramnik 4-2 last year, there’s not much doubt that it is better than any human chess player.
Rybka is available as a plug-in chess engine, which means that you also need to have a chess graphical user interface (GUI) to use it. There are a variety of GUI’s available, including the free Arena GUI.
Rybka plays wonderful chess of course. It is free of all the problems that used to plague computer programs–for example it freely sacrifices material for positional compensation. Nevertheless, it’s not the program that I prefer, for a couple reasons.
First, it is only available for Windows (and Linux using Wine), and I wanted a program for Mac OS X. The strongest program for Macs is clearly Hiarcs 11, developed by Mark Uniacke. Although Hiarcs 11 seems to be somewhat weaker than Rybka, it is still stronger than Deep Fritz, and any human being.
Most importantly, on Macs, Hiarcs is paired with the very nice chess “Sigma Chess” GUI. This GUI/engine combination sports the absolutely crucial feature, missing from any version of Rybka, that you can adjust its strength down to any level from world champion to amateur levels as low as 1250 Elo. If you don’t know what 1250 Elo means, you’re probably an amateur who will lose to a 1250–it’s the level amateurs typically reach after playing in tournaments for about one year. (Note: to obtain this feature on the Mac, you’ll need to spend $20 to get the “Pro” version of Sigma Chess, plus $50 for Hiarcs 11. You should also be able to adjust the level of Hiarcs on Windows GUI’s like Arena, although I have no personal experience with this.)
Amazingly, at whatever level you choose, Hiarcs plays a very human-like game. Previous computer programs, when weakened, played poorly strategically, but still did not make tactical errors. A weakened Hiarcs will make tactical mistakes that you can take advantage of, and will also play at an appropriate level of strategic understanding, so there is no particular reason to adopt anti-computer approaches when playing against it.
Of course, Hiarcs comes with many other features, including the ability to use it to analyze your games. Most grandmasters use these programs to aid in their training, and Hiarcs is well-known as one of the best engines to use.
Personally, I also enjoy just watching my Hiarcs 11.2 engine play blitz chess against the 11.1 engine that I previously used. It’s like watching a couple world champions duke it out. I think it’s worth appreciating, that at least for the game of chess, we now have $50-$70 software running on commodity hardware, that essentially passes the Turing test.
If you are a beginner, you might be better off choosing the mass-market Chessmaster, which comes packed with a lot of nice tutorials, as well as some very weak opponents to start with. However, I don’t like Chessmaster as much as Hiarcs because the weakened opponents in Chessmaster have the strong-tactics weak-strategy characteristics of computer programs that become so tiresome after a while.