Monday, February 16, 2026

OSR Mars Campaign Update - Leigh Brackett Mars OSR Campaign Elements - Warriors of the Red Planet

 A Leigh Brackett-style Mars campaign for an Old-School Renaissance (OSR) game moves away from the "superheroic" feel of John Carter and toward a gritty, "Sword & Science" noir. Her Mars is a dying, dusty world where ancient civilizations are being encroached upon by cynical Earth corporations and hard-boiled mercenaries.


This blog entry picks right up from 

OSR Mars Campaign Update : Dying World- Warriors of the Red Planet

Below is a framework for building this campaign using OSR principles (high lethality, player agency, and discovery).


1. The Setting: The Dying Red World

Brackett’s Mars is a mournful, cold, and arid planet. It is a "planetary romance" where science is ancient and often indistinguishable from magic.

  • Atmosphere: Breathable but thin. The ecology depends on the annual summer melting of the polar ice caps.

  • The Landscape: Dried-up sea bottoms, weathered ruins of cities a million years old, and bustling "Trade Cities" like Kahora, where Earthmen indulge in vices.

  • The Conflict: The "Company" (Terran corporate interests) exploits the planet’s resources while decadent Martian city-states and nomadic tribes resist or rot from within.

Key Locations

LocationDescription
KahoraThe primary Trade City for Earth. A domed, luxurious, and "civilized" hub of corruption and trade.
SinharatA legendary "lost city" in the desert, often associated with ancient mind-transference secrets.
Valkis & JekkaraLowland towns known for lawlessness, thieves, and "houses of pleasure" like Madame Kan’s.
The NorlandsThe bitter, frozen region near the North Pole, home to the mysterious "Thinkers" and Ice Creatures.

2. Character Classes & Archetypes

In an OSR system (like Worlds Without Number or Warriors of the Red Planet), players should feel like "tough but damaged" survivors.

  • The Outlander (Fighter/Thief): Like Eric John Stark. Often an Earthman raised in harsh conditions (e.g., Mercury) who is feral, cynical, and highly capable in a fight.

  • The Martian Noble/Witch (Magic-User): Members of the old races who use "psychic powers" or "ancient science" (radium pistols, mind-transference, or life-draining talismans).

  • The Mercenary (Fighter): A former spacer or gun-runner looking for a score in the desert ruins.

  • The Scavenger (Specialist): Experts at finding and operating ancient artifacts like the Shanga rays (rejuvenation tech that can be addictive and dangerous).


3. Campaign Themes & Mechanics

To capture the Brackett vibe, incorporate these specific elements:

The "Decadence" Mechanic

Unlike many OSR games where "Gold equals XP," consider a system where spending credits on vices in Trade Cities (like Shanga ray parlors) provides a temporary mental/physical boost but risks addiction or "devolution" into primitive forms.

Tech as Magic

Artifacts should be rare and terrifying.

  • The Shanga Rays: Can make a person feel younger but are described as a "stimulant to the brain's pleasure centers."

  • Mind Transference: Ancient Martians can swap bodies, leading to "who is who?" social mysteries.

  • Radium Pistols: High-damage, but ammunition is scarce and the technology is often poorly understood by the user.


4. Sample Adventure Hook: The Jewel of Ban Cruach

The players are hired in a smoky tavern in Jekkara to escort a dying Martian named Camar to the northern city of Kushat.

  • The MacGuffin: Camar carries an ancient talisman that "flames in the blood."

  • The Twist: The "Company" wants it for its energy potential, while a barbarian queen (the "Black Amazon") wants it to awaken an army of Ice Creatures.

  • OSR Challenge: The players must manage water supplies while crossing the "Gates of Death" mountain pass, dealing with both corporate patrols and telepathic Martian nomads.Blending C.L. Moore into a Leigh Brackett setting transforms "Dying Mars" from a gritty adventure into a psychedelic, cosmic horror. While Brackett provides the dusty streets and the gun-smoke, Moore provides the alien geometry, the soul-draining terrors, and the hauntingly beautiful goddesses.

    To infuse your OSR campaign with the spirit of Moore (specifically her Northwest Smith stories), we focus on the uncanny.


    1. The Moore-Brackett Synthesis

    In this campaign, the "Lowlands" are Brackett territory (crime and grit), but the "Highlands" and the "Sunken Vaults" are pure Moore—places where the laws of physics are thin.

    • The Atmosphere: Add descriptions of "impossible colors," smells of ozone and ancient incense, and a constant sense of being watched by things that aren't quite alive.

    • The Horror: Monsters shouldn't just be "beasts"; they should be psychic parasites. They don't want to eat your meat; they want to taste your life force.


    2. New Class: The Life-Witch (Magic-User Variant)

    In Moore’s world, power is intimate and terrifying.

    • The Trade-off: Instead of spell slots, the Life-Witch uses their own HP (Life Force) to fuel effects.

    • Abilities: They can project "vibrations" that freeze an enemy's heart or weave illusions that reflect a target's deepest desire.

    • The Risk: Every time they use power, there is a chance of attracting a Dweller in the Void—a cosmic predator that can smell "open" minds.


    3. The "Vaults of Color": A Moore-Inspired Dungeon

    Replace a standard dungeon with a "Vault of Color." These are non-Euclidean spaces where the Martian "Gods" (actually extra-dimensional entities) still sleep.

    Room Mechanics: The Sensory Warp

    • Whispering Walls: Players must make Save vs. Wisdom or be compelled to touch a surface that drains 1d4 HP per round.

    • The Shambleau Room: An encounter with a creature that appears as a beautiful, red-haired woman with a "turban" that hides a mass of psychic tentacles. It offers a "pleasure so intense it kills."


    4. Strange Artifacts & Relics

    Use these items to replace standard "magic items." They should feel alien and slightly repulsive.

    ItemThe "Moore" Twist
    The Black Stone of JhaAllows the user to see through walls, but it slowly turns the user’s eyes into cold, black glass.
    The Thirsty DaggerA blade of translucent crystal. It deals $+2$ damage, but if it doesn't taste blood once a day, it begins to vibrate, dealing damage to the wielder.
    Song-JewelsSmall gems that play a melody capable of putting a crowd into a trance. The melody is actually a distress signal for a god-like entity from the void.

    5. Factions: The Moore Influence

    • The Cult of the Faceless: A group of Martians who have literally traded their features (eyes, mouths) for psychic "All-Sight." They serve entities like Yig or the Dark Mother.

    • The Gray Ones: Not aliens, but Earthmen who have stayed in the Martian "Dead Cities" too long and have become partially transparent, losing their connection to reality.


    6. Adventure Hook: The Scarlet Song of the Dry Sea

    The party finds a "living map"—a piece of skin that pulses with light. It leads to a temple in the center of the Dry Sea where a woman named Yvala (a Moore-style siren) is singing a song that is literally causing the Earthmen in nearby Kahora to go catatonic.

    The players must reach her before their own "vibrations" are tuned to her deadly frequency.

    • OSR Stakes: Do they kill her to save the city, or do they try to steal her "Song-Jewel" to sell to the Company, risking their very souls in the process? In the tradition of Brackett and Moore, mutation isn't just physical—it’s a psychic rot, a "devolution" into the eldritch past of the Solar System. When a character spends too much time in the Sunken Vaults or is kissed by a Shambleau, roll on the table below.

      The Mechanics of Decay

      • Minor Exposure: Roll 1d50. These are often aesthetic or sensory.

      • Major Exposure: Roll 1d100. These involve structural changes to the soul and body.

      • The "Moore" Save: A successful Save vs. Magic/Science can delay the onset, but the "vibration" remains in the character's blood forever.


      The Martian Mutation & Corruption Table

      d100ResultEffect
      01-05The Gilded IrisEyes turn a metallic, swirling gold. You can see heat signatures but suffer -2 to saves vs. light-based attacks.
      06-10Ozone BreathYour breath smells of lightning and ancient tombs. Animals are instinctively terrified of you.
      11-15Transparent SkinYour skin becomes like parchment; veins are visible. +1 to Stealth in shadows, but take double damage from fire/heat.
      16-20The Thirsty VoiceYour voice becomes a melodic, hypnotic rasp. +2 to Charisma checks, but you must drink twice the normal amount of water.
      21-25Vestigial FeathersFine, iridescent "down" grows on your forearms. They vibrate when "Ancient Science" is nearby.
      26-30Brackish BloodYour blood turns black and thick like oil. You are immune to terrestrial poisons, but healing magic/tech is only 50% effective.
      31-35The Hollow BoneYour skeleton becomes porous and light. You can jump twice as far, but take +1 damage from all physical bludgeoning.
      36-40Prehensile TongueYour tongue grows long and black. You can taste "emotions" in the air (detect lies on a 1-in-6 chance).
      41-45Crystalline ScarsOld wounds heal into jagged, violet quartz. Natural Armor +1, but your Dexterity drops by 1.
      46-50The Shadow-LagYour shadow moves 1 second slower than you do. It occasionally points toward the nearest "Source of Life."
      51-55Psychic HemophiliaWhen you take damage, nearby allies must save or take 1d4 psychic damage from your "mental scream."
      56-60The Serpent’s UnhingeYour jaw can unhinge. You can swallow small objects (keys, gems) for safekeeping, but lose the ability to speak clearly.
      61-65Dimensional PhasingYour hands occasionally become misty. You can reach through thin doors, but have a 10% chance to drop any weapon you hold.
      66-70The Red FeverYour skin turns the color of Martian dust. You no longer need to breathe air, but you must submerge in Martian sand daily.
      71-75Extra-Sensory FeelersFine, hair-like tentacles grow from your scalp. You cannot be surprised, but "Noisy" environments cause 1 damage/turn.
      76-80The Devouring EyeA third eye opens on your palm. It can cast Sleep once per day, but it "eats" 1 point of your Intelligence permanently on a natural 1.
      81-85Geometric LimbsYour arms grow slightly elongated and move in "impossible" angles. Your reach increases by 5ft, but you look monstrous.
      86-90The Soul-EchoYou begin to remember the lives of the Martians who died in the room you are standing in. Risk of temporary insanity.
      91-95The Shambleau KissYou grow thick, scarlet "hair" that is actually a parasite. It grants +4 Strength but slowly drains 1 CON per week until you die.
      96-99Astral DisplacementYou are no longer fully in this dimension. You take half damage from non-magical weapons but cannot touch gold or silver.
      00Becoming the GodYour physical form dissolves into a pillar of "Black Light." Character is retired and becomes a regional "Entity" or boss.

      5. Using Corruption in Play

      In a Moore-inspired campaign, mutation is a narrative weight. * The Social Cost: In a Brackett Trade City like Kahora, anyone with a roll of 50+ is viewed as a "Leper of the Vaults" and will be shot on sight by Company guards.

      • The Benefit: These mutations often provide the only way to survive the deeper, weirder "Moore-zones" where standard human biology simply fails.In the intersection of Brackett’s "Science-Noir" and Moore’s "Cosmic Decadence," drugs and rituals are never just mechanical buffs. They are desperate gambles. They are how a dying race tries to remember its glory, and how Earthmen try to survive a world that fundamentally rejects their biology.


        I. Martian Pharmacopeia (The Drugs)

        Martian chemistry is less about biology and more about vibrational frequency.

        SubstanceStreet NameEffectThe "Moore" Withdrawal
        Khusat DustThe Red SleepAllows the user to survive without water/air for 1d6 days by entering a death-like trance.Upon waking, the user is "haunted" by a psychic shadow that mirrors their movements for 24 hours.
        Valkis BlueIce-FireA liquid distilled from northern fungi. Grants +2 to Hit and immunity to fear for 1 hour.Once it wears off, the world appears grey and "thin." -4 to all Wisdom saves until the user sleeps 12 hours.
        Shanga ResinLiquid GoldSqueezed from ancient rejuvenation machines. Heals 2d8 HP and restores youthful vigor.Highly addictive. If taken more than 3 times, the user begins to "devolve," growing primitive, thick brow ridges or scales.
        The Silver VaporGhost-SmokeInhaled via ornate Martian pipes. Allows the user to see "The Invisible" (spirits, phased entities, hidden doors).The user’s physical body becomes brittle. Any physical hit taken while under the influence is an automatic Critical Hit.
        Iskander’s TearsThe TruthA black, viscous oil dropped into the eyes. Grants telepathic "hearing" for 10 minutes.The user hears everyone’s thoughts simultaneously. Save vs. Madness or suffer a permanent nervous tic.

        II. The Rituals of the Dying Sun

        These are not "spells" in the Vancian sense. They are grueling, atmospheric procedures that require specific conditions—often celestial alignments or horrific sacrifices.

        1. The Rite of the Transferred Soul

        • Purpose: To swap the consciousness of two beings. (Commonly used by ancient Martian nobles to steal young Earthmen's bodies).

        • The Ritual: Requires a "Coil of Vulcanized Glass" and the two subjects to be bathed in the light of both Phobos and Deimos simultaneously.

        • OSR Risk: There is a 1-in-6 chance the souls "mingle." The survivor gains the other's memories but suffers a split personality.

        2. The Invocation of the Black Fire

        • Purpose: To summon a "Dweller from the Void" (a Moore-style entity) to destroy an enemy.

        • The Ritual: The caster must spill their own blood into a "singing bowl" made of Martian meteor-iron and chant the forbidden names of Jha.

        • OSR Risk: The entity is not controlled. It consumes the target, then checks to see if the caster is "tasty" enough to be next.

        3. The Song of Rejuvenation

        • Purpose: To purge the body of "The Corruption" or mutations.

        • The Ritual: Conducted in the ruins of the Sunken Vaults. A Martian "Singer" must perform a 12-hour melody while the patient is submerged in a vat of bio-conductive slime.

        • OSR Risk: The ritual "resets" the DNA. The mutation is gone, but the character loses 1d4 points from a random Attribute as the cost of the biological "re-write."


        III. Adventure Hook: The Vendor of Visions

        A merchant in the Jekkara spice market is selling a new drug called "The Veil of Moore." It doesn't just give visions; it physically transports the user's mind to a lush, prehistoric Mars.

        The Problem: People aren't coming back. Their bodies remain in Jekkara, slowly turning into crystalline statues, while their minds are trapped in a psychic "paradise" that is actually a feeding ground for an ancient, star-born parasite.

        • The Mission: The players must take the drug themselves to enter the "Dream Mars," find the trapped souls, and sever the psychic tether before their own bodies turn to stone. 

To map Leigh Brackett’s Mars, you must envision a planet of verticality and decay. The "Highlands" are the ancestral homes of the dry, telepathic Martian aristocracy, while the "Lowlands"—the beds of evaporated ancient seas—are the frontier for Earth’s corporate greed and the haunt of Moore’s cosmic horrors.


I. The Global Geography (The Red Grimoire)

1. The Great Dry Sea (The Lowlands)

This is the heart of the campaign. Once a vast ocean, it is now a salt-encrusted desert of red sand and "dust-ships" (sand-skiffs).

  • Jekkara: The "City of the Lowlands." A lawless port where Earthmen trade radium for Martian artifacts. Famous for its red-light district and the "Thieves' Market."

  • Valkis: A twin city to Jekkara, even more decadent. It sits on the edge of the Sea of Dead Dreams, where the veil between dimensions is thinnest (Pure Moore territory).

2. The Polar North (The Norlands)

A bitter, frozen waste where the "Ice Creatures" dwell.

  • Kushat: A city of black stone built into a glacier. It is the center of the Shanga Ray trade.

  • The Gates of Death: A narrow mountain pass that is the only land route to the pole. It is haunted by "The Thinkers," telepathic entities that feed on travelers' fear.

3. The Highlands (The Ancient Plateaus)

  • Sinharat: The "Lost City." A sprawling ruin of ivory towers that supposedly holds the secret to immortality through mind-transference.

  • The Mountains of White Cloud: Home to the "Black Amazons"—a matriarchal society of fierce warriors who guard the ancient "Lightning Swords."


II. Strategic Locations & Points of Interest

RegionKey LandmarkThe "Moore" Influence
The Dead Sea BedThe Pillar of JhaA 500ft obsidian needle that hums a frequency that causes hallucinations.
The Martian EquatorialKahora (Trade City)A domed city of neon and glass; the "Earthman's Oasis" in a hostile world.
The Sunken VaultsThe Temple of YvalaAn underwater city (now dry) where the geometry is "wrong" and non-Euclidean.
The Crimson DesertThe Singing SandsDunes that emit a psychic "song" that can lure travelers to their deaths.

III. The "Point-Crawl" Map Structure

In an OSR campaign, don't worry about hex-mapping every inch. Use a Point-Crawl map where locations are connected by dangerous "Trade Routes."

  • Route A: The Smuggler’s Run. (Kahora $\rightarrow$ Jekkara). High corporate presence, frequent patrols, but safe from monsters.

  • Route B: The Path of Skulls. (Jekkara $\rightarrow$ Sinharat). Requires a specialized guide (like "Glass-Eye" Garreth). High risk of psychic storms and "Void-Dwellers."

  • Route C: The Frozen Maw. (Valkis $\rightarrow$ The Norlands). Extreme environmental hazards (cold, lack of oxygen).


IV. The Map's "Hidden Layer"

In this setting, the map has a Third Dimension: The Subterranean.

Beneath the red dust lies a planet-wide network of "The Old Tunnels." These are ancient maintenance shafts for the planet's failing atmosphere-processors.

  • Travel Perk: Fast travel between cities away from the sun.

  • Travel Risk: They are infested with "The Gray Ones"—humans who stayed in the dark too long and became ghoulish cannibals.

Gemini said

In the vast, evaporated seabeds of the Red Planet, the environment is as much of an antagonist as any radium-toting mercenary. Crossing the Dry Sea requires grit; crossing it while the "Moore-ish" psychic veils are thin requires a miracle.

Roll d100 once per day of travel, or whenever the party makes a loud commotion (e.g., a radium pistol firefight).


The Martian Wastes: Travel Complications

d100EventDescription & OSR Mechanic
01-05The Saffron SimoomA storm of toxic yellow dust. 1d6 damage/turn without masks. Vision reduced to 2ft.
06-10Corporate Patrol2d4 Company Enforcers on sand-skiffs. They demand "Transit Permits" (200 credits) or a bribe.
11-15Singing SandsThe dunes hum a Moore-style melody. Save vs. Magic or wander 1d6 miles in the wrong direction.
16-20Water PoisoningThe nearest oasis is tainted with "Ancient Salts." +1 Mutation point if consumed.
21-25Mirage of the PastA psychic projection of a lush, watery Mars. 1-in-6 chance a player tries to "swim" in the sand.
26-30Radium LeakA player’s weapon/artifact begins to glow and hiss. It must be vented or it explodes in 1d4 rounds.
31-35The Gray Scavengers1d10 devolved Martians set an ambush using "Invisible Wire" across the trail.
36-40Phobic AlignmentPhobos and Deimos align. Gravity fluctuates; all movement is halved, but jumping distance triples.
41-45The Thirsty StoneThe party finds a beautiful gem. It provides light but consumes 1 ration of water per night from the holder.
46-50Abandoned Sand-SkiffHalf-buried in a dune. Contains 1d100 credits but is haunted by a Soul-Echo (Wraith).
51-55Non-Euclidean FoldThe trail ahead loops. The party ends up back where they started the day unless they use a "Star-Compass."
56-60The Black Amazon ScoutA lone warrior on a giant lizard. She offers a "Blood-Truce" for information on the Company.
61-65Ozone PocketThe air becomes hyper-oxygenated. Everyone gains +2 to Initiative but becomes irritable and violent.
66-70Sky-Whale CarcassA massive, drifting gas-beast has died. Its belly is full of "Lighter-than-air" gas (valuable but explosive).
71-75The Whispering WindThe wind carries the voices of the party’s dead loved ones. Save vs. Sanity or suffer -2 to all rolls today.
76-80Atmosphere Pump FailureThe air grows thin. Heavy exertion (combat) causes 1d4 Stamina damage per round.
81-85Ancient PylonA buzzing metal spire. Touching it restores all "Tech" charges but triggers a Mutation Roll.
86-90The Dweller’s ShadowA massive, semi-transparent entity passes overhead. If the party moves, it attacks. If they stay still, they survive.
91-95Shambleau SporesRed filaments drift in the air. If they touch skin, they begin to "root." Requires fire to remove.
96-99The Vault EntranceA trapdoor in the sand leads to a "Moore-Vault." High risk, high reward.
00The Red RainIt rains literal blood for one hour. All Martian creatures become frenzied; Earthmen feel a strange, primal sorrow.

The "Brackett" Rule of Travel

In her stories, the desert isn't just empty space; it's a graveyard. Every failed roll on this table should reveal a piece of Forbidden History.

“The wind didn’t just blow the sand; it spoke in the voices of kings who had been dust since before the first ape stood upright on Earth.”

The Logistics of Survival

  • Water: In the Lowlands, water is currency. If the party runs out, they don't just take damage; they begin to see the "Moore-visions" (hallucinations that lead to ancient, hungry traps).

  • Radium: Radium pistols are the "Magic Missiles" of this setting. They don't use ammo counts; they use Usage Die (start at d12, roll after every fight; on a 1-2, the die shrinks. At d4, it’s empty).


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