This is not my first foray into 'alternative Popcultural history megadungeons' but what is a first is how it comes fast it comes together. Our first tentative steps into this alternative history begins in 1947 with the continuation of the Occult World War with the crash of the Roswell UFO out in the New Mexico desert. This was merely another Grey scouting mission in a World War II that had turned cold after the Nazi feeling of Earth & into Antarctic.
The United States government had their latest developments in the discovery of hyperdrive from the downed Grey space craft. Meanwhile the Nazi had developed their own craft in trade deals with the Derro for their own Vril drive. The Vril drive off shoot itself from the interstellar craft of the serpent men of Valusia.
It was about this era when the first appearance of a growing & excited company would appear to create the first of the ion drives derived from the retro engineered alien saucers & some principles observed on Gort's craft. YoYo Dyne Propulsion began several top secret US government contracts & research under the fledging Area 51 umbrella.
In 1954 the world got its first wake up call of the highly dangerous mutant menace of giant mutated ants, humanoids, & monsters beyond the pal of mankind!
Its from here that I'd love to add in one of my favorite Night Owl Workshop games Raiders of the Lost Artifacts to the mix to really give this one a pulpy OSR feel.