Infinity: Secrets of the Necropolis mod for Duke Nukem 3D

After having rid Los Angeles and the rest of the world and solar system of
aliens (or so he thought) Duke decides to take a well-deserved vacation. So
he packs his bags and heads to the Mediterranean to relax and enjoy the
sites. Among the sites he visits is a museum. But after exploring the museum
for a short while he begins to notice a subtle similarity between the Greek
artifacts and some of the things he'd seen in the aliens' domain. He gets
suspicious and starts exploring further. He begins to discover clues that
lead him to a secret passage hidden beneath the museum. There he finds an
alien artifact which provides him with evidence that the alien invasion was
not a recent development.

The aliens had originally infiltrated Earth's civilization nearly 3000 years ago,
during the Classical Greek era.
Duke also discover that the "artifact" is actually a machine of sorts, a link to
the ancient world. He realizes now that there may be other such links and
the aliens could return once again. He decides the only real way to defeat
them once and for all is to travel back to their original source and destroy
them there. After some experimentation he gets the link to work and finds
himself traveling back to ancient Athens. He first finds himself in a village
and must find the trail of evidence that will lead him to the alien source. He
discovers that the aliens have presented themselves to the Greek people as
gods, having them build great temples to worship and honor them.

The aliens have infested the Acropolis and Duke must destroy them! After clearing the
Acropolis he thinks his work is finally done. He is just about to celebrate
his victory when he discovers there is yet another temple, a hidden temple,
unknown to modern day archeologists and ancient Greeks alike. He follows the
trail to the temple and there he makes yet another startling discovery.