[Astromancer]

Try this one...

This Q4 low Mana parallel is going through a rather pulpy version to the 1930s. Complete with trips to the moon (the UK, France, Germany, Russia, and the USA have moonbases, the Empires of Brazil and Japan are planning on building their own), supertech, and masked mystery men and women. They also have the more "normal" stuff of the 1930s (although the USA is notably less racist, sexist, and homophobic, than Homeline was in the 1970s, no one knows why).

However this parallel Earth is being invaded by aliens. Unlike a conventional pulp alien invasion, these aliens are only TL3! They're still a threat to this TL6^ Earth because they have Magic!

Basically, a pulp 1930s being invaded by a Sword and Sorcery/ Planetary Romance world. Sure the invaders have Wizards and scraps of Barsoom-style super technology, but 1930s Earth is no walk in the park. But do let Conan and Red Sonja run into Doc Savage and the Shadow,