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Mars, also known as Tir and Barsoom (especially the Martian Dreamlands) among the Red Martians.

"[Randolph Carter] gazed at the cyclopean ruins that sprawl over Mars' ruddy disc...."
- H.P. Lovecraft, "Through the Gates of the Silver Key (fiction)"

A post-apocalyptic wasteland, a desert world of attenuated atmosphere and dried oceans dotted with ruins of dead civilizations built on the ruins of other civilizations of even greater antiquity.

Origin: Mars is a fan-made setting for Cthulhu Icarus based on 19th and early 20th Century science fiction literature and film.

Supporting Materials (if any)

Mars might be considered a sub-setting of Cthulhu Icarus, using the "future" character sheet found in Cthulhu Through The Ages.

The Dreamlands of Barsoom can be considered an exotic extension of the standard Dreamlands setting, using the Dreamlands character sheet. See the page on Barsoom for more information about this setting.


Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

By Lovecraft's time, Mars was largely regarded as a dying world from which the atmosphere and oceans had vanished, covered in red deserts and perhaps scarred with the doomed ruins of alien canals desperately carved into the world's surface in a hopeless bid to water long-deserted cities and parched farmlands; this description is assumed to be true for the purposes of this setting.


Once home to horned gods of terrifying intellect and power, waking Mars today is a dead world, consisting of vast stretches of dried seabeds, stagnant canals choked by masses of Red Creeper, crumbling Martian ruins dotting the bleak desert landscape and barely distinguishable from desolate, wind-blasted rocks, hills and mountains, and a few wretched survivors lurking in remote corners of the world where they subsist on water ice and a dwindling supply of food.

By the Hyborian Age, the Horned Martians were all but completely extinct, replaced by humanoid Martians known as Yorhis, who in turn would replace themselves with their lesser descendants, the Aihais, specially engineered to survive Mars' now harsh climate.

Mars today is a hopeless tomb-world, where deteriorating populations of more or less humanoid survivors hide far from the Sun in chilly, moldering underground vaults, slowly going mad and decaying in varying degrees into shocking savagery; the last remaining remnants of humanoid Martian civilization have abandoned this desert world and these degenerate survivors, fleeing into the Martian Dreamlands, known as "Barsoom", from the coming of the alien Uliri invaders.

What little remained of life on the waking Martian surface was largely stripped away centuries ago by the tentacled Uliri invaders, who had turned their eyes toward conquest of Earth, even as mankind on Earth have turned their eyes toward exploration of Mars.

At some point in recent Martian history, travelers brought deadly Earthly bacteria to Mars; the unprepared Uliri invaders and any organisms they brought to Mars with them, such as Red Creeper, virtually decimating these organisms by the 21st Century, and preparing the way for colonists from Earth to make what remains of Mars their home.

The Dreamland of Barsoom is the last bastion of most native life for this dying world, and the last refuge for Martian Dreamers to escape their planet's doom.

Martian Dreamlands (Barsoom)

See Barsoom.

Martian Canals

TO DO Yahan Canal




The Aihais city of Ignarh, straddling the Yahan Canal and spanned by a great bridge, is known to its inhabitants as Ignar-Vath on the east bank, and the more modern Ignar-Luth on the west bank, where it is populated by human visitors to Mars.


The hideously ancient city of Yoh-Vombis is perhaps one of the last known ruins of Yorhis civilization.

Olympus Mons


Valley Dor


River Iss






Associated Mythos Elements


Keeper Notes

There is, of course, no direct relationship between the versions of Mars presented by H.G. Wells and Edgar Rice Burroughs, other than the assumption of an ancient, dying Mars populated by diverse aliens (or, at least in Wells' case, the invading Martians, and the humanoid things they brought with them as food). Similarly, there is no direct link between these writers, and Lovecraft's fiction (aside from the dubious qualification of tentacles on Wells' Martians, and the tenuous similarities between Burroughs' John Carter stories and Lovecraft's Dream Quest of Unknown Kadath, or any of the above with Quatermass and the Pit (1967 film).

Rather, these elements were put together with a greater or lesser degree of awkwardness in filling in gaps between each other; feel free to adjust these elements in any way that seems appropriate to you. Some options here might include focusing only on Wells' Martian Invasion aspect, or on a Pulp Cthulhu adventure in Burroughs' Barsoom (which seems, for all intents and purposes, to be a kind of Dreamland), or use bits of the Quatermass-inspired human creation story to construct the contents of the fevered rantings of mad cultists in their blasphemous tomes.

There are, of course, a tremendous number of varieties of Martians in Burroughs' fiction alone; most keepers might find it best to only use two or three different varieties of Martians in any given campaign.

A traditional E.R. Burroughs-style Barsoomian planetary romance campaign might best be suited to a "pulp" Cthulhu treatment, while a slower-paced archaeological exploration of the secrets hidden in abandoned Martian ruins or a Martian invasion story might work perfectly as a more "vanilla" Call of Cthulhu scenario.