With some digging, found an applet to play it.http://multivac.fatburen.org/~ivan/pyraosapplet.html
However, it looks like it is only against other players on a server few (if anyone) connect to (no one was on when I connected).
For that matter, given that the docs
on the server protocol were last updated in '01, the server might not be up either.
Still, a stop closer to online play for those looking for it.