Back in September I reported that Critter may be the best engine around for endgame analysis. I recently ran the position given in the post on January 29 titled Two Knights Ending through a gamut of engines. The first time around each engine was given ONE minute to select a move. To be fair I then ran the same position giving the engines THREE minutes. All engines selected the only winning move (1.Nc6) with the following evaluations.
ENGINE ONE min. THREE min.
Critter 1.6a 64 bit mate in 29 mate in 28
Stockfish 2.3.1 JA 64 97.39 mate in 26
Fritz 12 (1 CPU) 12.50 10.98
Fire xTreme 10.26 13.75
Ivanhoe B47 cBx64a 8.93 12.17
Strelka 5.5 (1 CPU) 2.67 25.87
Komodo64.3 2.33 2.32
Rybka 2.3.2a mp 0.87 0.87
Houdini 1.5 0.56 15.72
Rybka 3 (1 CPU) 0.49 1.23
Naum 4.2 0.33 0.30
Spike 1.4 0.24 0.00
Dual core laptop, 512 hash. Critter website
From what I have been able to glean, in tactical situations Stockfish would be the engine of choice, but if you are playing on sites like ICCF or LSS where engines are allowed, you are rarely going to get into tactical positions. Openings, positional play and endings are going to be the order of the day.
It should be pointed out that the commercial version of Houdini (v. 3) will easily defeat any of these free engines though. Houdini 3 costs about 40 Euros ($53) but I do not use it because it supports up to 6 cores and 4 GB of hash. My laptop does not have that much computing power, so I don’t feel the expense is worth it.
Speaking of openings, Sedat Canbaz has produced Perfect 2011 Opening Book that is compatible with various GUIs. This opening book is based on Super GM games (average 2650 Elo) and is tuned and optimized for the strongest lines for the playing styles of the top 20 chess engines in engine vs. engine play. Note however that the book’s depth is only up to 8 moves. When it comes to engine vs. engine play (such as you are likely to run into on ICCF or LSS), opening books play a vital role and are the key for getting a high Elo performance and as the author points out, it is wrong to view openings based only on engine evaluations.