The Spracklens made significant improvements on the original SARGON program and released Sargon II. In 1978 it tied for third at the ninth North American Computer Chess Championship despite being seeded ninth of 12 entries. Sargon finished only behind Belle and Chess 4.7, and defeated AWIT—running on a $5 million Amdahl mainframe—amazing the audience. That year they published a series of articles in BYTE on computer chess programming, stating "we think it would be nice if not everyone had to reinvent the wheel".

Sargon II was ported to a variety of personal computers popular in the early 1980s. The game engine featured multiple levels of lookahead to make it more accessible to beginning chess players. BYTE in 1980 estimated that Sargon II had a 1500 rating at the highest tournament-time difficulty level, and speculated that it was the best chess program on sale, including dedicated devices.