Old Japanese mapset, ten maps, with version for both First and Second Encounter.
The Fuhrer's Ambition, the first of our curated picks, is a 10-level mapset released in 1996-1997 in two different versions: for the First and Second Encounter. While the former is obviously limited to what's available in the shareware version, the latter makes use of the new weapons and enemies, and if you've played the 1st Enc. version first, there's a small surprise waiting for you at the end. Many enemies too. I'll be frank though, this is not the best mapping in the world. Still worth a try, if not simply for curiosity's sake.
There's also a short storyline attached. At some unspecified time, some neo-Nazis are still trying to conquer the world. Their last hope is an advanced and mysterious military base called "The Fuhrer". The base is located under a city, so it cannot be bombed, therefore you're tasked with infiltrating the place, discovering who or what is there (geee, I sure wonder who!) and destroying it.
You can choose between the First and Second Encounter editions in the episode selection screen.
===Credits===
Yoshimichi Endoh. This is one of those obscure mods that Clubey fished out of the Japanese community.