GNU Chess Mac 4.0 is a free chess game for the Macintosh derived 
from GNU Chess 4.0 available on other platforms. It is distributed 
under a GNU Public License and may be given away, but not sold. 
 
Version 4.0b5 adds the ability to save and restore games and the
often requested "Undo" for people that make mistakes.
 
        -- Dan Oetting <oetting@gldfs.cr.usgs.gov>