OSR Commentary Adventures on Mars By ODD74 & Warriors of The Red Planet By NightOwl Workshop

 We've had a semi permanent Warriors of the Red Planet game on going for a long while. The PC's have been skirting  the Dark Martian lands of H.G. Well's War of the Worlds books. Now the Invasion of Earth happened a long while ago. DM Steve has trotted out the OD&D forum's Adventures on Mars ODD74 book from  thread.   Scroll down to the last entry by Bastet1002's CLICK HERE!: Adventures on Mars (UPDATED WITH COVER!). And grab this one! 
Adventures on Mars By ODD74 adds a ton of  Lovecraftian monsters, Dark Martians, Orks, and more. Even though the supplement is meant for original Dungeons & Dragons, it can easily be adapted for Warriors of the Red Planet rpg. For a really good overview of Warriors of the Red Planet check out the Mutant Wiki entry. 

Back to the Aventures on Mars By ODD74 and the 'abandoned' Dark Martian cities which have caches of Dark Martians still living and maintaining them in DM Steve's games. The Dark Martians also have deep ties to the Kaldanines within the implied Adventures campaign setting. There are at least seven Dark Martian  cities that we've had to deal with. These are protected by walkers sunking in the sands of Mars. 
Let's not mention the fact that we've got two mega dungeons in the area. And this goes back to some commentary again from the Barsoom entry on the Mutant Future wiki enty; "Barsoom is a world of high adventure and intrigue! The world is dying, made somewhat livable by artificial means. Civilization is technologically advanced, but is suffering form social and technological stagnation. The red martian sands hide the ruins of untold civilizations. The many city-states dotting the red landscape are always at war, be it on ground or by great flees of airships, with fragile alliances and betrayals around every corner. The cites are suspended technological marvels from a bygone age" 
What Adventures on Mars does is expand the scope of that adventure & campaign setting to deal with things hinted in the Edgar Rice Burroughs books and dealt with in the Leigh Brackett novels.