Sigma Chess
www.sigmachess.com/home.html
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Sigma Chess is a master strength Macintosh chess program for both OS X and Classic Mac OS. The feature set includes: Optional HIARCS engine, UCI Engine support, Databases, PGN/EPD, basic desktop publishing, endgame databases, novice levels, a true perspec