Critter is a cross-platform UCI chess engine by Slovakian programmer Richard Vida which is free for non-commercial use.
The engine has achieved top five on most official chess engine Elo rating lists.
[1][2][3][4] Richard Vida started working on Critter in late 2008.
The first version was originally written in Object Pascal but the code was later converted to C++ using Bitboard technology because Delphi did not perform well under 64-bit processors.
[5][6] Critter had its over-the-board (OTB) debut at the ICT 2012, where it became a strong runner-up behind the Rybka cluster.