OSR Commentary Adapting C1: The Hidden Shrine of Tamoachan To The Barrows & Borderlands Rpg

 

Adapting the classic C1: The Hidden Shrine of Tamoachan to the Barrows & Borderlands (B&B) framework requires shifting the focus from standard dungeon crawling to a high-stakes, survival-horror "extraction" crawl. This blog post picks right up from Adapting X2 Castle Amber (Chateau d' Amberville) By Tom Moldvay For Barrows & Borderlands Rpg

In B&B, the primary antagonist isn't just the monsters—it’s the Poisonous Gas and the ticking clock of your party’s resources.

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### The Core Hook: The Suffocation Mechanic

In B&B, environmental hazards are lethal. As soon as the players fall into the ruins, they are affected by the Miasma of the Sunless Shrine.

• The Clock: Every 10 minutes (one Dungeon Turn) of exploration, players must tick off 1 Ration or Torch to represent the extra effort of breathing/moving through the thick dust.

• The Penalty: If the party stops for a Long Rest, every character must make a Vigor Save. On a failure, they gain the Fatigued condition, reducing their maximum Grit until they reach fresh air.

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### Converting Key Encounters

Barrows & Borderlands thrives on "Weird Fantasy" tropes. Here is how to reskin the iconic Tamoachan threats:

Original Element	B&B Adaptation	Mechanical Twist
The Giant Slug	The Slime-Crusted Horror	Acts as a "Terrain Hazard." Its trail forces an Agility Save or the character is Stuck.
The Vampire (Zotzilaha)	The Hemomancer Wraith	Instead of level drain, it drains Grit directly. If Grit hits 0, the player becomes a Thrall.
The Doppelganger	The Echo-Shifter	It doesn't just look like a PC; it copies the last Ability the PC used against it.
The Gas Traps	The Blight Vents	These deal direct Inventory Damage. Instead of HP, the gas rots 1d4 random items in the backpack.

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### The "Borderlands" Twist: Loot and Relics

Since B&B emphasizes the value of "The Haul," the Olman treasures should be more than just gold.

• The Mirror of Itzpapalotl: In B&B, this acts as a cursed focus. It allows a caster to double their spell range, but every use requires a Sanity Check.

• The Jade Mask: This functions as a "High-Tier Helm." It grants immunity to the shrine's poisonous gas but prevents the wearer from speaking or casting spells with verbal components.

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### Navigation & Hazard Levels

To maintain the B&B "Meatgrinder" feel, divide the shrine into three distinct Hazard Zones:

1. The Lower Chambers (The Crawl): Focus on Vigor and Agility. Heavy on pit traps and collapsing ceilings.

2. The Middle Tier (The Ritual): Focus on Wits and Lore. This is where the environmental puzzles and "The Centaur" reside.

3. The Upper Tier (The Breach): Focus on Combat and Speed. The gas is thickest here; players must find the exit before their Gear Slots are depleted by rot and exhaustion.

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Design Note: Use the B&B Reaction Table for the various guardians (like the Giant Crayfish). Not everything in Tamoachan wants to kill the players immediately; some might be willing to trade "Safe Air" locations for the party’s precious supplies.

Gemini said

In Barrows & Borderlands, guardians aren't just bags of hit points; they are atmospheric hurdles that test a party’s resources, sanity, and tactical positioning. To fit the "Borderlands" feel, these Olman guardians should feel like ancient, semi-sentient bio-mechanical or spirit-bound constructs.

Here are the primary guardians of Tamoachan adapted with B&B mechanics:

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### 1. The Teotl-Amoxtli (The Tome Guardian)

Originally a giant crayfish, in the B&B version, this is a massive, chitinous horror fused with obsidian shards, guarding the sunken bridge.

• Hazard Level: High (Physical)

• Key Attribute: Armor 4 (Obsidian Shell).

• The Threat: Its claws don't just deal damage; they have the Sunder quality. On a successful hit, the player must sacrifice 1 Defense Item (Shield or Armor) or take double Grit damage.

• The Twist: It is bioluminescent. If killed, its internal fluids can be harvested to create 3 Durable Torches that burn underwater and in gas.

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### 2. The Zotzilaha Vampire (The Bat God’s Avatar)

Instead of a traditional vampire, this is a desiccated, leathery humanoid suspended in a glass vat of preservative "God-Blood."

• Hazard Level: Extreme (Supernatural)

• The Draining Gaze: Anyone making eye contact must pass a Spirit Save. Failure results in the Weakened condition—all Physical checks are at a disadvantage until the player consumes a full Ration.

• Echo-Flight: It does not walk; it blurs between locations. Melee attacks against it suffer a -2 penalty unless the room is illuminated by more than one light source.

• The Loot: The Heart of Zotzilaha. Can be crushed to instantly restore all Grit to the party, but inflicts a Permanent Scaring on the user's soul.

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### 3. The Nahual (The Jaguar-Man)

The classic shapeshifter of the shrine, re-imagined as a "Shadow-Stalker" that haunts the party through the ventilation shafts.

• Hazard Level: Medium (Stealth/Ambush)

• Stalking Mechanic: The Nahual does not attack head-on. Every time the party rolls a "1" on an Exploration check, the Nahual strikes the person at the back of the marching order and vanishes.

• Prowess: It ignores the first 2 points of damage from non-silvered weapons.

• Weakness: It is terrified of True Fire. A torch held high keeps it at bay, but using a torch in the gas-filled lower levels risks an explosion.

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### 4. The Kulkulkan Construct (The Feathered Sentinel)

A mechanical serpent made of gold, jade, and feathered silk, coiled around the central pillar of the upper tiers.

• Hazard Level: High (Environmental)

• The Coiling Constriction: Instead of biting, it wraps around a target. The target is Restrained and loses 1d6 Grit per turn from crushing force.

• Jade Scales: The construct is immune to Poison and Bleed effects.

• Tactical Solution: The construct is powered by a large gemstone in its forehead. A character can attempt a Wits Check to jam the mechanism with a crowbar or tool, bypassing the fight entirely.

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### Guardian Stat Block Template (B&B Style)

Guardian	Grit	Saves (V/A/W/S)	Special Ability
Obsidian Horror	22	15 / 8 / 5 / 10	Sunder: Destroys gear on a Crit.
Bat Avatar	18	8 / 14 / 16 / 15	Lifesteal: Heals 1d4 on hit.
Shadow Jaguar	12	10 / 18 / 12 / 8	Vanish: Disappears after attacking.
Jade Serpent	25	16 / 12 / 8 / 5	Heavy: Cannot be pushed or tripped.

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### Management of "The Haul"

In B&B, these guardians are often standing on top of Relics. When a guardian is defeated, roll on the Ancient Olman Loot Table:

1. Macuahuitl of Woe: A wooden sword embedded with obsidian. Deals +2 damage but breaks (is removed from inventory) on a natural 1.

2. Chacmool Basin: A stone bowl that purifies any liquid placed inside, turning it into Clean Water (1 Usage).

3. Quetzal Cloak: Grants the wearer a +4 bonus to Agility Saves involving jumping or falling.

Adapting X2 Castle Amber (Chateau d' Amberville) By Tom Moldvay For Barrows & Borderlands Rpg

 

Barrows & Borderlands (B&B) is an indie OSR (Old School Renaissance) powerhouse that mashes together 1970s-style tabletop gaming with a "cracked-reactor" aesthetic. If you’ve ever wanted to play a game where a 17th-century pikeman and a psychic mutant explore a radioactive dungeon, this is it.  This blog post picks up from Adapting B4 The Lost City By Tom Moldvay.For Barrows & Borderlands Rpg

Pairing it with the classic module X2: Castle Amber is a match made in weird-fiction heaven. Here is the breakdown of the system and how it interfaces with that legendary module.

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1. The System: Barrows & Borderlands

Created by Matthew Tapp, B&B is technically a bridge between OD&D (0E) and 1st Edition AD&D, but with a heavy dose of pulp science-fantasy. It is typically sold as a four-volume "Little Brown Book" style set or a single "Black Label" omnibus.

Core Pillars

• The Vibe: "Solomon Kane fighting a sorcerer with a raygun while riding a velociraptor." It’s dark, radioactive, and unapologetically "gonzo."

• The Rules: It uses the DNA of early D&D but adds "swingy" mechanics like Roll-to-Cast magic (where spells can literally blow up in your face) and a dedicated Psionic Duel system.

• Classes: Beyond the classic Fighting-Man and Thief, you get the Gamma (a mutant scavenger) and the Psychic.

• Radiation & Mutation: The world is a wasteland; players frequently deal with fallout, black-powder weapon misfires, and bizarre physical mutations.

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2. The Module: Castle Amber (X2)

Originally written by Tom Moldvay for the D&D Expert Set in 1981, Castle Amber (Château d'Amberville) is widely considered one of the "weirdest" modules in D&D history.

Why It Fits B&B

Castle Amber isn't a standard dungeon crawl—it's a surrealist fever dream.

• The Plot: The party is trapped in a magical mist and forced to enter the mansion of the Amber family—a clan of insane, bored, and immortal nobles.

• Literary Roots: It is heavily inspired by Clark Ashton Smith’s Averoigne stories and Edgar Allan Poe.

• The "Weird" Factor: You’ll find things like an indoor forest, a banquet hall with undead diners, and a trip to a parallel-Earth version of medieval France.

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3. Running Castle Amber in B&B

Because B&B is built on the bones of Original D&D, it is 95% compatible with Castle Amber out of the box. However, the B&B flavor transforms the experience:

Element	Standard D&D Feel	Barrows & Borderlands Feel
The Ambers	Eccentric wizards.	Radiated, psionic-warping aristocrats.
The Mist	Magical barrier.	A shimmering wall of chronal radiation.
Combat	Tactical swordplay.	Flintlocks barking in narrow hallways while the Gamma player tries to eat a brain collector.
Magic	Predictable slots.	High-stakes gambles where a "Magic-User" might accidentally summon a cosmic horror instead of a Shield spell.

Pro-Tip: Use the B&B Radiation Tables for the Grey Mist surrounding the castle. Instead of just being "deadly," make it cause minor mutations or psychic echoes for those who touch it.

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4. Why This Pair Works

Both products share a "Pulp Weird" soul. Castle Amber is often criticized by "serious" gamers for being too random or chaotic. Barrows & Borderlands, however, thrives on that chaos. The Amber family’s bizarre sense of humor and reality-warping mansion feel perfectly at home in a world where "star-metal" and "black powder" coexist

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.