Colossus 4 Chess

Bryant started Colossus Chess in 1983, using his White Knight Mk 11 program, winner of the 1983 European Microcomputer Chess Championship, as a basis. It was developed on an Apple II, but was first commercially released for Commodore 64 as Colossus Chess 2.0 (CDS Micro Systems, 1984). A number of releases for 8-bit microcomputers followed. Version 3.0 was released in 1984 for the Atari 8-bit computers (published by English Software), followed by 4.0 in 1985 which was released on most formats of the day (published by CDS). As other games of the time, the Acorn Electron implementation required that part of the screen memory be used as working space.

Colossus Chess featured time-controlled play with game clocks, an opening book with 3,000 positions, and problem-solving mode that could solve normal mates, selfmates and helpmates. Pondering on opponent's time and a three-dimensional chessboard were introduced in Colossus Chess 4.0. All releases were written in the assembly language of the appropriate CPU; the ZX Spectrum version could examine an average of 170 positions per second.

Info gave Colossus Chess IV for the Commodore 64 three stars out of five, stating that it was less attractive but "a darn sight more playable" than Chessmaster 2000 with both keyboard and joystick controls. The magazine warned of the difficulty of remembering the "shifted keyboard control sequences" and said it was "badly in need of a quick-reference card".