Microchess , a chess-playing program for microcomputers, has been described
as the first commercially successful game for home computers, initially
programmed in 1976 on MOS Technology’s KIM-1.

Designed for homebrew kit hobbyists to plug into less than 1k of memory, what
the play algorithms lack in grandmaster talent they make up for in speed.
Marginally upgraded (the TRS-80 version expanded to 4k: 2k for game logic and
2k for a picture of a chess board) for the burgeoning microcomputer market
(why restrict input and output to a hex keyboard and 6 LED digit displays if
you don’t have to?) it went on to sell over a million copies for the Apple 2
and TRS-80 (and, among the usual suspects, also eventually ported to other
hobby platforms such as those made by “Processor Technology, Imsai, Cromemco,
Polymorphic Systems, MITS, Ohio Scientific, and many more”) before quickly
being overtaken by the likes of Sargon.

Microchess