The comments in lisp/play/gomoku.el (line 39) point to 
http://renju.nu/r1rulhis.htm which is now an HTTP 404
error.

The page is now at http://renju.se/rif/r1rulhis.htm.

This is not critical since it is only a comment for people who read 
sources and would like more info
on the history of the game. Also, the comment was written ca. 1988 and 
nowadays wikipedia can provide a more
stable alternative.

I attach a possible patch.

-phs