> is "games/trek/USD.doc/Makefile" broken?

It's not broken. But you'll need to go fetch bsd.doc.mk from the attic
and install groff and unless you only want to look at the glorious ASCII
art, a ps viewer like gv.

https://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/share/mk/Attic/bsd.doc.mk?rev=1.8&content-type=text/plain