The Moon Maid remains one of my all time favorite series of the Edgar Rice Burroughs. This is a classic series of exploration set within the world of 2026.
The Earth is expanding out into the stars and mankind has exchanged knowledge with Barsoom. Both worlds are the richer for the experience. War, poverty, etc. are pretty much banished and mankind has mounted an expedition to Barsoom.
Things go terribly wrong.
According to wiki :
THE PARADOX OF THE MOON by Den Valdron addresses some of the major concerns about using this classic.
The Gygaxian biology and other paradoxes of the series are also settled as well LUNAR LOST WORLDS by Den Valdron
Using The Moon Maiden In Your OSR games
The Moon Maiden and its follow up Red Hawk are part of what might be considered one of the alternative time lines that ERBs wrote and designed. His moon was not only active and dangerous but part of a push for a very invasive people who not only bred with Earth women but ruled the Earth in Red Hawk.
There's a post apocalyptic feel to the books as if Earth was on the edge of something very catastrophic and The events of Red Hawk simply pushes it over into the void. Believe it or not these books would make an excellent setting for a 'Mutant Future' game. The action takes place within the interior of the Moon and not on its surface.
Much of what we see of the Moon is a dying ecology and a race of people ready for expansion or extinction. The humans come right into the middle of this mess. This is a perfect time for adventurers to stumble into this mess. What happens after the events of Red Hawk though? What possible treasures are left on the moon?
Let's throw in ERB psyche powers as well!