Mac Chess

MacChess is a free, master-strength chess program for the Macintosh by Wim van Beusekom, copyright 1999. Version 5.01 is the PowerPC-native release; a parallel 2.5.1 build remained available for 68K Macs. MacChess 2.5 was for years the most-downloaded file in the AOL Mac Board Games library, with more than 26,000 downloads.

Engine strength

In the 1997 Aegon Computer-Human tournament, MacChess defeated a master and a near-master while running on a low-end 200 MHz PowerPC 603. Version 5.01 reworked the search engine to find forced mates faster in a more compact codebase, and added accurate "mate in N" announcements.

New in 5.01

The 5.01 release introduced more than 18 features over MacChess 4.0: a large-board option with Classic and American piece sets, a Learning Chess instructional file, an opening book expanded by nearly 12,000 positions, doubled endgame test scores, sudden-death and increment time controls, and independently configurable clocks for White and Black.

Analysis features

MacChess supports continual background analysis while the user moves pieces manually, copy/paste of EPD and PGN positions, ECO opening codes, animated VCR-style game playback, hint, takeback, and printable graphical diagrams. Five piece sets ship with the program.

System requirements

Version 5.01 needs a Power Macintosh with 5.4 MB of free RAM and System 7 or higher. It is not ExaChess-compatible. Distribution is free; commercial CD-ROM redistribution requires the author's permission.