CHEOPS Chess project is a C chess engine.
CHEOPS (CHEss OPponent Simulator), or Χεοψ, is a fully-functional AI chess program capable of human vs. human, human vs. computer, and computer vs. computer play. It uses a 64-square linear array board representation.
The game tree search is alpha-beta, and the static evaluation function considers material, mobility, and motif features.
CHEOPS comes with extensive documentation on the program internals, aimed at students or programmers wishing to understand or extend the system.
Product's homepage