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Home * Engines * Critter

an UCI compliant chess engine by Richard Vida, executables freely available for personal use to run under Windows, Linux, Android and Mac OS [2] . Starting in late 2008, Critter was first written in Object Pascal compiled with Delphi, now available as open source engine [3] [4], and was ported to C / C++ in 2009 [5] . It consistently evolved through various board representations from 0x88 to bitboards, as acknowledged by Richard Vida, also incorporating ideas from strong open source programs like Ippolit [6] , to a world class engine which achieved top five of most engine rating lists [7]. In 2012, Critter had its over the board debut at the ICT 2012, where it became strong runner-up behind the Rybka cluster.


Critter applies a principal variation search with aspiration windows, null move pruning [8] and other state of the art forward pruning, reduction and extension techniques, such as the Botvinnik-Markoff extensions [9] . It can search in parallel with up to eight threads [10] , supports Gaviota tablebases [11] , and is able to play Chess960 [12] . Critter features a tapered eval with a score pair class and overloaded operators [13] [14] , and blockage detection in late endgames [15] .

Selected Games

ICT 2012, round 7, Rybka - Critter [16] [17]

[Event "ICT12"]
[Site "Leiden"]
[Date "2012.05.13"]
[Round "7"]
[White "Rybka"]
[Black "Critter"]
[Result "1/2-1/2"]

1.d4 d5 2.c4 e6 3.Nf3 c6 4.e3 Bd6 5.b3 f5 6.Bd3 Nf6 7.O-O Qe7 8.Bb2 O-O
9.Qc1 b6 10.Ba3 Bb7 11.Bxd6 Qxd6 12.Nc3 dxc4 13.Bxc4 Nbd7 14.Re1 b5
15.Bd3 b4 16.Na4 c5 17.Nxc5 Bxf3 18.gxf3 Rfc8 19.Bc4 Nxc5 20.dxc5 Rxc5
21.a3 bxa3 22.Qxa3 Nd5 23.Red1 Qc7 24.Kg2 Rd8 25.Bxd5 Rdxd5 26.Qa4 Qe7
27.Rxd5 Rxd5 28.Qxa7 Qxa7 29.Rxa7 Rb5 30.Re7 Rb6 31.Kg3 Kf8 32.Rd7 Rxb3
33.Kf4 Rb5 34.h4 h6 35.Kg3 Rb8 36.h5 Re8 37.Rb7 Re7 38.Rb5 Kf7 39.e4 Kf6
40.exf5 exf5 41.Kf4 Re2 42.Rxf5+ Ke6 43.Rb5 Rxf2 44.Rb6+ Kf7 45.Rb7+ Kf6


Forum Posts




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