A strange game. How did the King end up in f3 in the first place.
The free Macintosh chess game current version is 2.4.1 Copyright 2008. A GNU chess product.
Application Universal.
According to sources
GNU Chess: Frequently Asked Questions
Apple's chess product has not been updated.
Normally even in the Monitor feature a Chess Software Program should indicate mate, or freeze if a move is attempted after mate.
Apple no longer included Chess in the latest Operating System.
The strongest Chess program for Macintosh available is Sigma/Hiarchs. Two versions.
One for the new Intel Macs. The other for all other Macs.
See:
ATPM 7.02 - Review: Mac Chess Downloads
and
Sigma Chess - Macintosh Chess Software
SigmaChess does have a free version.
The full version for regular Macs is $15. Hiarchs additional cost.