Adapting B4 The Lost City By Tom Moldvay.For Barrows & Borderlands Rpg

  This blog post picks right up from What classic D&D module should I run for Barrows & Borderlands?

B4 The Lost City (1982) by Tom Moldvay (TSR)

Levels 1 - 3 (and beyond)

Adapting the classic B4: The Lost City for a system like Barrows & Borderlands (a hack of Mousritter or similar OSR-adjacent games) is a fantastic project. You’re essentially shifting from "Human pulp adventure" to "Small-scale survival horror."

The tone shifts from Indiana Jones to something much more claustrophobic and desperate. Here is how to bridge the gap between the modular desert tomb and your tiny heroes.

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1. The Scale Shift

In the original, the ziggurat is massive. For Barrows & Borderlands, scale is your best friend for building atmosphere.

• The Environment: The "sand" of the desert feels like impassable, shifting mountains. The ziggurat isn't just a building; it’s an artificial mountain range.

• Verticality: Since your characters are small, use the collapsed sections of the ziggurat to create "climbing puzzles." A broken staircase is now a treacherous cliff face requiring hooks and ropes.

2. Converting the Factions

The heart of The Lost City is the three mask-wearing factions (Cynidiceans). In a rodent-centric RPG, these shouldn't just be humans in masks—they should be different species or "afflicted" critters.

Original Faction	B&B Interpretation	Vibe
Brotherhood of Gorm	The Iron-Whiskers	Stoic, armored hamsters or squirrels. They maintain the upper tiers and value "The Old Law."
Magi of Usamigaras	The Glitter-Paws	Illusionist mice who use shiny scavenged beads and glass. Very secretive and prone to riddles.
Maidens of Madarua	The Spear-Sisters	Fierce shrews or rats. They are the most proactive and likely to hire the players for "pest control" (killing Zargon’s cultists).

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3. The Monster Conversions

Standard D&D monsters are too "big" for B&B. You need to translate the threat level, not just the stats.

• Zargon: Instead of a giant tentacled humanoid, imagine Zargon as a massively mutated, ancient Sludge-Toad or a monstrous, multi-eyed Star-Mole that has been warped by the pyramid's depths.

• Cynidiceans: Treat them as "Hollow Ones"—creatures that have lost their spark, wandering in a drug-induced or magical stupor.

• The Hive: Replace giant bees or beetles with Clockwork Scarabs or Shadow-Spiders that hunt by vibration.

4. Mechanics & Inventory Management

Burrows & Borderlands thrives on resource scarcity. The Lost City is a "resource sink" dungeon.

• The Light Problem: In a tomb, light is life. If the players run out of matches or glow-moss, the "Lost" part of the title becomes very literal.

• The Mask Mechanic: Make the faction masks Inventory Items. Wearing one grants "Safety" in certain zones but takes up a precious slot and might impose a "Disadvantage" on hearing or sight.

• Scavenging: The Cynidicean tiers are full of "treasures" that are useless to humans but gold to mice—a rusted sewing needle (a masterwork rapier), a thimble (a sturdy helmet), or a single dried raisin (a week’s worth of iron rations).

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Implementation Tip: The "Dream" State

The original module has the inhabitants living in a drug-induced haze. In B&B, you can make this more "magical." The air in the lower levels could be thick with Lotus Pollen.

Rule: Every Turn spent in a "Pollen Room" requires a Save. Failure means the PC begins to see the ruined ziggurat as a lush, golden palace, making them ignore actual traps or predators.

 For a Burrows & Borderlands conversion, let’s focus on the Brotherhood of Gorm. In the original, they are the "lawful" warriors. In a rodent-centric world, they become the Gilded Sentinels—an order of aging golden hamsters who guard the upper thresholds.

Here is Kanadius, the Grandmaster of the Iron Whiskers.

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Kanadius, The Last Shield-Bite

Title: Grandmaster of the Gilded Sentinels (Brotherhood of Gorm) Species: Ancient Golden Hamster Disposition: Honorable, exhausted, and slightly delusional.

Kanadius wears a heavy mask of beaten brass shaped like a stern human face. He speaks in a booming baritone that rattles his tiny ribcage, firmly believing he is a giant knight of old. He refuses to acknowledge he is a hamster living in a ruin.

Attributes & Vitals

• STR: 14 | DEX: 8 | WIL: 13

• HP: 8 | Armor: 2 (Ancient Plate & Brass Mask)

• Morale: 10

Gear & Stashes

• The Storm-Needle (Medium): A blue-tinted darning needle that crackles with static. Deals d6 damage; on a critical hit, the target is Cleaved (paralyzed) by a spark.

• The Great Seal: A heavy wax-stamped coin used as a shield.

• Blue Lotus Snuff: A small pouch of powder. If consumed, Kanadius ignores the first 4 points of Damage taken, but becomes "Confused" regarding friend and foe.

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Behavior & Traits

1. Oath-Bound: Kanadius will not attack unless the party violates the "Sanctity of the Threshold" (the entrance to Level 2) or refuses to bow to the Altar of Gorm.

2. Diminished Sight: Due to his heavy brass mask, Kanadius has Disadvantage on any checks involving sight or ranged reaction, but Advantage on saves against Fear or Mind-Control.

3. The Golden Haze: He often speaks to people who aren't there—specifically his "fallen legion."

Quest Hook: "The Iron Thimble"

Kanadius will grant the party passage and a Silver Map of the Upper Tier if they retrieve his lost "Great Helm" (a rusted metal thimble) from a nest of Shadow-Shrews in the ventilation shafts.

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How to Roleplay Kanadius

• The Voice: Deep, raspy, and overly formal. Use words like "thee," "thou," and "interloper."

• The Twitch: Despite his stoicism, his nose twitches uncontrollably when he smells fresh seeds or dried fruit, breaking his "noble knight" persona for a brief, embarrassing second.

GM Note: If the players manage to unmask Kanadius, his Morale immediately drops to 4. Without the mask, he realizes the world is dark, terrifying, and small, and he will likely flee to the nearest crevice.

 

Gemini said

Since Burrows & Borderlands is all about making the most of "human-sized" debris, this table focuses on the unique, gritty utility of a ruined ziggurat.

Rolling a d100 gives you a mix of survival essentials, "high-tier" gear for rodents, and evocative flavor that reinforces the scale.

The Cynidicean Scavenge Table (d100)

Roll	Item	Description
01-05	The Iron Spike	A rusted 2-inch nail. Functions as a Heavy spear ($d10$ damage) but requires two paws to wield.
06-10	Lotus Petal (Dried)	Can be brewed into a tea. Heals $1d6$ HP but causes "Hazy Vision" (Disadvantage on DEX) for 1 hour.
11-15	Golden Thread	3 feet of sturdy embroidery silk. Holds 10x the weight of normal twine.
16-20	Glass Shard (Blue)	From a broken potion vial. Sharp enough to be a dagger ($d6$). Glows faintly near magic.
21-25	Brass Thimble	Provides +1 Armor if worn as a helmet, but muffles hearing (Disadvantage on WIS).
26-30	Cynidicean Coin	A heavy gold-plated lead disc. Worth 50p to collectors, or a heavy improvised shield.
31-35	Stale Rations	A single, rock-hard almond or a dried raisin. Provides 2 days of food.
36-40	Matchstick (Unstruck)	A massive wooden pillar. Can be used as a torch (1 turn) or a heavy club ($d8$).
41-45	The Needle-Sword	A fine sewing needle with a decorative bead hilt. A Masterwork Light weapon ($d6$).
46-50	Paper Scrap	A fragment of a 1950s pulp comic. Can be used as a bandage or a primitive hang-glider.
51-55	Copper Ring	To a mouse, this is a heavy hula-hoop or a structural brace for a tunnel.
56-60	Rubber Band	Brittle but functional. Can be used to craft a high-tension trap or a slingshot.
61-65	Bottle Cap	A "Round Shield." Provides +2 Armor but clatters loudly (Disadvantage on Stealth).
66-70	Leather Strip	Cut from an old sandal. Enough material to repair 3 sets of armor.
71-75	Marble (Glass)	A "Boulder." Can be rolled down stairs to trigger traps or crush small foes ($d12$).
76-80	The Moth-Wing Cloak	A tattered, iridescent cape. Grants Advantage on Stealth in dim light.
81-85	Scented Oil	A vial of ancient perfume. Masking scent—predators cannot track you by smell.
86-90	Fish Hook	Extremely sharp. Can be used as a climbing grapnel or a wicked polearm ($d8$).
91-95	The Silver Key	A small luggage key. Likely opens a chest on a lower tier.
96-99	Bead of Power	A plastic pearl that hums. If smashed, creates a blinding flash (Stuns all in room).
00	The Relic	A working Zippo Lighter. To a mouse, this is a God-Tier artifact of Fire.

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How to use this table:

• Searching Tiers: For every 10 minutes (1 Turn) spent searching a room, have a player roll.

• The Weight of Loot: Remember that in B&B, many of these items (like the Marble or the Matchstick) are Heavy and might take up 2 slots or require two mice to carry.

• Flavoring the Finds: Describe the dust and the smell of ancient cedar as they pull these "relics" from the sand.

1d20 Random Encounters With Cosmic Contamination & Debris Table For Your Old School Campaigns

 There are some hazards that adventurers can't fight against or win, things that fall from the sky and infect the land with roiling horror and degeneration that runs deeper then any horror. There is a 60% chance that when these things happen that PC's might become infected themselves with the cosmic debris of an uncaring universe. There is also a 40% chance that the chaotic quasi dimensional affecting horror will not let the dead even rest quietly and 1d20 zombies or worse undead will heed the cosmic siren call of such visitors. Only expensive super science or magical treatments might heal such wounds but the damage goes much deeper into the victims of these events.

“It was just a colour out of space—a frightful messenger from unformed realms of infinity beyond all Nature as we know it; from realms whose mere existence stuns the brain and numbs us with the black extra-cosmic gulfs it throws open before our frenzied eyes.”
― H.P. Lovecraft, The Colour Out of Space and others

There is a 20% chance of any treasure or other artifacts taken from such areas of being infected with the damning radiations and strange magicks that accompany such weird cosmic visitors from beyond. Ancient and expensive magics might be able to take away the horrid taint that comes with these relics or perhaps not. The madness merely spreads.

1d20 Random Encounters With
Cosmic Contamination & Debris  Table

1. A fragment of cosmic debris from the body of Outer thing has fallen and reeks with the power cosmic from its former host. All within 40 feet of this thing must save vs death or gain 1d6 mutations. This might be cured with strong magicks. Wizards of course will want this fragment of idiotic god hood and pay 5000 or more gold pieces for it. 
2. The head of a cosmic god now crystallized has fallen into the landscape and is infecting everything with poisoned alien thoughts and dreams as it has dies and has for thousands of years. There are 1d6 goblinoid things that hatch from the ground around it every 1d4 days. 
3. From the outer planes has come a spray of incredibly weird prismatic colour infecting everything with a weird other worldly vitality. Add +3 to constitition and strength but in 1d6 days your body will burn itself out as you die spasming and writhing in pain as you explode for 1d8 points of damage unless you get expensive healing.  
4. Weird radiations have seeped in from a meteor that has fallen changing everyone's flesh to an odd blue and that's it but it has lowered their intelligence by -3 points and their now prone to violence and abnormal fights with all those around them. 
5. A decaying alien eye ball from a god thing has fallen releasing the spirits of 1d6 alien ghostly souls onto the landscape. They are now turning the locals into wraiths and giving birth to new nation of weird ghostly warriors who stalk the land insearch of souls.. Those who come in contact must save vs death or want to join them. 
6. A piece of cosmic debris has infected the landscape and now there are giant alien crystals stealing and collecting the souls of those around them. They are dangerous and very deadly. They're agenda and reasons are unknown. 
7. A sword from the hand of a cosmic giant has fallen, the violence and weird radiations are turning everything with a four mile radius into a murderous monster of alien and strange aspects. Should the artifact be removed then the mutations and effects will remain for years to come. 
8. A cosmic coffin from beyond the stars has fallen bring with it, the body of its alien occupant who has turned into an alien drug of incredibly potent aspect. There is a 2 mile drug induced haze surrounding those caught in it with a horrid mutating and rotting disease but they don't mind even as they fall apart. 
9. Weird hallucinogenic crystals have fallen releasing cosmic illusions that create mind shattering visas of reality for those who gaze into their surfaces. They are worth 700 gold pieces to certain mad cults and wizards but those who are exposed must make a save vs death or have their skin infected with the same other worldly qualities. 
10. 1d6 cosmic demonic hunters are after a meteor that has fallen and is now creating incredible fertility within those around a seven mile radius. The hunters consume the souls of those they encounter to find their quarry but it has taken on the aspect of a local pastor and come to be loved by those under his care. 
11. A strange cloud has come from the sky and increased the mutations with the local populations within a two mile radius. This strange god like life form is the memory of an ancient god thing that has died off and now is remaking the locals into his worshipers old images. The cloud leaves scriptures and odd messages of salvation on panes of glass and metal. Those enter this area have a 40% chance of being infected with the strange radiations. 
12. A piece of cosmic debris has become a parasitic lifeform and is infecting as well as mutating the locals in an effort to feed upon their souls. The thing will depart in 1d6 days after eating everything it can. Thing must be stopped. 
13. A cosmic shape shifter has moved into the area to consume the forms and flesh of the locals for its own purposes but it is actually merely a herd animal for a larger cosmic shepherd  who is coming to cull it from the local scenery in 1d6 days. The must be stopped and banished or the area will be destroyed in a rain of fire. 
14. A strange organ from some ancient demon from the Outer Darkness has fallen and is now creating 1d10 imps that are dragging off the souls and bodies of those they can into the great beyond for unknown infernal purposes. They must be stopped or the angels will come to destroy this place. 
15. A piece of alien god projectile vomit is giving birth to 1d6 alien things of 3 hit dice and 9 armor class that are trying to become animals but are consuming things to learn but it isn't working. They will cause untold destruction around them. 
16. The mating of two gods has created a horrid fluid which is causing the plants and animals it comes in contact to give birth to alien humanoid things that murder anyone they come in contact with in wild abandon glee. They use any weapons or tools they can.
17. An alien virus has fallen and is trying to take on the role of the gods but has only succeeded in angering the local demons and devils who will go to war with these invaders. The community is caught in the middle, alien radiations are seeping in from Outside as well.
18. A tendril from some giant alien god has fallen and now 1d8 warrior thralls have been given birth to by its presence. Those caught within a twenty foot radius from them must save vs death or begin to praise their idiotic dark master. The dead have risen to worship it.
19. 1d10 cosmic dead have come from the sky and the local dead are joining with them to praise a strange and ancient necrotic dark master from the sky. They're cult is growing and they shall leave for the stars in 1d6 days but not before feeding on the flesh of any locals they can to power their cosmic journey.
20. A colour from outer space has come to tend its young ones and take the souls of those around it to feed them. The alien radiations dance in the morning's light and within six days the whole place will consume itself unless you can stop it.
    
    

1d10 Random Weird Battlefield Encounters Table For Your Old School Campaigns

There are some strange vehicles and odd wrecks that adventures come across in the wastelands, here is a random encounter table for those strange twisted hulks that lay abandoned on the side of the road. Twisted hulks of metal  in an urban or country landscape just waiting for adventurers to come across them. 

These battlefields cross time, space, & even planes.The burning wreckage is often too tempting a target for looters, adventurers, along with the occasional salvagers. They become targets for some of the most vicious monsters that come to prey on the foolish, the damned, & the the lost. 

1d10 Random Weird Battlefield  Vehicle Loot Table

1. 1d8 small mini tanks each with some undead horror within it.These things are not what they appear to be at all. These things are actually twisted assassin robots built to resemble undead. There are 1d6 small minor relics in the tanks as well for salvage. 
2. A selection of strange jeep like vehicles part wreckage and part rotting organic something else. There are 1d6 goblin mutant things that will burst forth from sacks within these things. 1d8 minor super science relics are entwined in the pseudo organs of these things. 
3. A futuristic troop transport houses 1d6 free willed intelligent juju zombies with ray guns and a bad attitude. There are several power cells for super science weapons scattered about. 
4. A large twisted wreck of a hover car is waiting for tow truck that will never come. A zombie flays in the front seat and he has a watch, slug thrower, several freeze dried rations, and a Geiger counter. 
5. Some strange wreck glows faintly with weird ration. Any approaching with forty feet must make a radiation check. There are jewels, and ancient cash stashed aboard. 
6. A wrecked and twisted space craft waits for a crew who will never come. Several small swarms of mutant striges wait for anyone exploring this wreck.
7. This small wrecked space coop holds the skeletons of a male and female humanoid along with a small monkey. Two invisibility belts are present with six charges each. The skeletons will animate and attack anyone disturbing them. 
8. A medical hover craft has smashed itself into the Earth, there are trio of wights inside along with 1d4 super science medical devices and a 1d3 healing potions. 
9. This is the shattered remains of a corvette class space craft that holds 1d8 ghouls and some minor relics and artifacts. This thing holds a valuable gold bar that happens to be radioactive. Any coming within 20 feet of this thing must make a radiation check. 
10. This wrecked flying car holds four ancient undead horrors just waiting for someone to unleash them. They each have a ray gun and guard an ancient energy jewel that will burn any that touches it for 3d6 points of damage.
    
    

1d6 Random Ancient Minor Treasures of Clark Aston Smith's Forbidden Places & Vaults Table For Your Old School Campaigns

 There are minor treasures that have been left behind in the wake of ages past in the vaults & tombs of ancient & vastly dangerous peoples. These items are tinged with the irony of ages past & wreathed in the mystique of forbidden history.

“Stern and white as a tomb, older than the memory of the dead, and built by men or devils beyond the recording of myth, is the mansion in which we dwell.”
― Clark Ashton Smith, The Return of the Sorcerer



1d6 Random Ancient Minor Treasures
of Clark Aston Smith's  Forbidden Places
& Vaults Table

1. A beautifully wrought dagger of gold & jet worth over 7,000 gold pieces created in the time of the ancient  sorcerers. This dagger is able to pierce & cut the shadowed heart of a scoundrel exposing the dark half of the soul able to remove it from its victim unless a save vs wands is made to resist the forbidden magicks of the dagger. The victim experiences harrowing visions of the Outer Darkness as their evil half is exposed to cold influence of weird space & time. 
2. The Scroll of Hypnos - This piece and fragment of parchment is actually a piece of dried skin of a slain god upon writ is the forbidden lore of dreams. There are 1d8 2nd level black magical spells but the scroll's real power is suspend the soul of its owner between dimensions in dreams where they may either gain wisdom or meet the lord of dreams who may or may not be pleased to see them. 
3. The Fragment of the Frog Demon - A weirdly wrought piece of slime laden scroll work capable of summoning a frog demon of extremely elegant malevolence who will create experiences of sorcerous power and wisdom. The owner will gain two levels of black magic and wizardly experience but the owner will also experience the machinations of the demon in nightmares for the rest of their lives and transform into an undead Deep One zombie servant in death bound for eternity to the frog demon. 
4. The Wand of Wandering Lust & Trepidation - This finely created wand of ivory & sandal wood is empowered with the forbidden energies of the lust pits of Atlantis. The wand is able to reach into the Outer Darkness between worlds & send into the dreams of its victims forbidden and harrowing visions of depraved alien lusts. The victims must save vs spell or wisdom to avoid suffering these night terrors which may after 1d20 months kill them in their sleep.  
5. The Goblinoid Glass - This glass has been impregnated with the blood & visions of fairies. Those gazing through it may be bodily drawn into the timeless realms of goblins & dangerous Fey creatures. The owner of the glass may direct an adventurer into the forbidden places of Dream. Care should be taken as the glass has a fickle and iconic sense of humor. 
6. The Fist of the Cat God - A jewel from forbidden Mu, this fist sized gem is able to transform the owner into a Cat From Mu. An ancient & now extinct cat species from ancient Mu about the size of a a prehistoric cat. These cats now roam certain areas of the Dreamlands, the owner of the Fist is able to see through the eyes of the transformed as a wizard eye's spell for twenty two hours at a time. The transformed has dark vision, the ability to hide in shadows, and some of the thief classes abilities. Those who submit to the gem's abilities must consume two quarts of milk in the name of the cat god or be transformed into a kitten permanently if certain costly sacrifices are not made on its behalf.
   
   Many of these treasures have been in the collection of the Fairy Queen Mab before the sinking of Atlantis & her influence has kept these things from the world of men for centuries. There is a 30% chance of her attention being alerted any time they are found and used. She is fickle and very dangerous in matters of the occult and forbidden.
   
   
   Of our studies it is impossible to speak, since they held so slight a connection with anything of the world as living men conceive it. They were of that vaster and more appalling universe of dim entity and consciousness which lies deeper than matter, time, and space, and whose existence we suspect only in certain forms of sleep — those rare dreams beyond dreams which come never to common men, and but once or twice in the lifetime of imaginative men. The cosmos of our waking knowledge, born from such an universe as a bubble is born from the pipe of a jester, touches it only as such a bubble may touch its sardonic source when sucked back by the jester's whim. Men of learning suspect it little and ignore it mostly. Wise men have interpreted dreams, and the gods have laughed. One man with Oriental eyes has said that all time and space are relative, and men have laughed. But even that man with Oriental eyes has done no more than suspect...
   HP Lovecraft Hypnos 1922