OSR Adventure Commentary - Adapting C2 The Ghost Tower of Inverness by Allen Hammack to the Hyperborea role-playing game

One of the most remarkable yet frequently overlooked First Edition AD&D modules ideal for OSR-style play is C2: The Ghost Tower of Inverness (by Allen Hammack, 1980). This blog post picks right up from 

OSR Classic Module Commentary - Deeper Integration of B1 In Search of The Unknown By Mike Carr Into the Hyperborea Rpg - Rival Adventuring party & The Pig Faced Orcs Gryth-Kin (Boar-Swine Mutant Thralls)

While overshadowed by famous TSR tournament modules like Tomb of Horrors (S1) or White Plume Mountain (S2), Ghost Tower offers a masterclass in weird, pulp-fantasy dungeon design that fits the modern OSR paradigm far better than many of its contemporaries.

The Setup & Pitch

The characters are convicts offered a pardon by the Duke of Urnst if they retrieve the Soul Gem from the ruins of Inverness—a fortress destroyed long ago by a reality-warping magical cataclysm. The tower itself exists primarily in a displaced, ethereal state, creating a surreal environment where classic dungeon crawling intersects with strange, cosmic physics.

Why It Excels for OSR Play

1. Non-Euclidean, Vertical Layout

Instead of a standard horizontal grid, the core of the module takes place inside the four levels of the ethereal tower, each corresponding to one of the traditional Four Elements (Air, Earth, Fire, Water). The geometry inside the tower is distorted:

• The Air Level: Gravity is localized or non-existent, forcing players to navigate vertical space, floating obstacles, and wind currents using creative problem-solving rather than basic movement speeds.

• The Fire Level: Features a literal giant chessboard environment, but executed with hazard-based logic that rewards player cleverness over arbitrary system checks.

2. Environmental Puzzles & Player-Skill Focus

OSR design prioritizes player skill over character sheet stats, and Ghost Tower is built entirely on this principle:

• Hazards cannot be bypassed with a simple "Disable Device" or perception check.

• Puzzles rely on understanding environmental cues, light manipulation, and the physical properties of the elements inside the displaced plane.

3. The "Time-Loop" & Displaced Reality Mechanics

At the pinnacle of the tower, players encounter the Soul Gem, which bends time and space around it. Interacting with the centerpiece of the dungeon triggers temporal anomalies:

• The dungeon reacts dynamically to the party’s actions rather than remaining a static set of rooms.

• Players can experience strange "echoes" of past adventurers or structural resets if they trigger specific traps, forcing them to map both space and state changes.

4. High Lethality with Organic Faction Opportunities

While designed for 8th–10th level characters, the module translates effortlessly to lower-level OSR retroclones (like OSRIC, Old-School Essentials, or Shadowdark) simply by treating combat as a last resort. The strange inhabitants inside the tower—trapped spirits, displaced monsters, and rival adventuring parties—often have motives beyond "attack on sight," opening up room for negotiation and trickery.

OSR Adaptability Checklist

• System Compatibility: Runs natively in OSRIC, Advanced Labyrinth Lord, or Hyperborea without modification. For Basic/Expert (B/X) or OSE, simply use standard Monster Manual equivalents for any 1e-specific spells or monsters.

• Prep Time: Medium. The module is relatively short (around 20–24 pages), but the Referee should sketch a cross-section diagram of the four elemental levels to easily track vertical movement and gravitational shifts.

• Key Treasure: The Soul Gem serves as a perfect campaign-ending artifact, a high-stakes patron quest-item, or a catalyst for planar travel.

Adapting C2: The Ghost Tower of Inverness into Hyperborea (3rd Edition / AS&SH) fits naturally into the setting’s weird fantasy, sword-and-sorcery, and cosmic horror tone. The core premise—a ancient ruined keep housing a reality-distorted tower and a soul-stealing artifact—aligns seamlessly with the ancient, dying world of Hyperborea.

Setting the Scene & Narrative Hook

In Hyperborea, replace the Duke of Urnst with a tyrant or sorcerer-king from one of the major city-states:

• The Hook: The party consists of prisoners or desperate mercenaries tasked by a High Priest of Thaumaturge in Khromarium or a Patrician of Viridistan to retrieve the Soul Gem (or Jewel of the Nether-Spire).

• The Location: Place the ruined fortress on the bleak, windswept plains of the Barren Wastes, near the Gull-Cliffs, or tucked within the eerie fog of the Spiral Mountain Range. The dungeon is not merely a displaced wizard's tower; it is a remnant of an ancient Hyperborean or Atlantean magico-technological experiment that pierced the fabric of the Black Gulf.

System & Mechanical Conversions

1. Level & Class Equivalents

• C2 was designed for AD&D levels 8–10. In Hyperborea, levels 6–8 offer the ideal balance of high danger, heroic resilience, and reliance on player ingenuity over trivializing spells.

• Class Mapping:

  • Clannish Fighters / Barbarians excel in the physical elemental trials.

  • Magicians and Pyromancers feel right at home with the tower's elemental themes.

  • Warlock, Necromancer, or Witch PCs will find the Soul Gem’s corruptive energy particularly tantalizing.

2. Vril, Sorcery & Horror (Saving Throws)

• Replace standard AD&D saving throws with Hyperborea's 5 core saves: Death, Transformation, Device, Avoidance, and Spell.

• Sorcery & Corruption: The ethereal aura inside the tower requires periodic Transformation or Spell saves against corruption or psychic distress. Unprotected exposure to the Soul Gem should provoke Vril-radiation or sanity-bending hallucinations.

Re-skinning the Elemental Levels

Hyperborea leans heavily into weird science, hyper-geometry, and Lovecraftian dread. Transform the four elemental levels to reflect this:

Level	Original C2 Concept	Hyperborea Adaptation
Level 1	Air Level (Zero Gravity / Wind)	The Void Level: Zero-gravity ambient chamber filled with floating, iridescent spores. Falling upwards into the freezing Black Gulf vacuum is a real risk if magnetic boots or ropes aren't used.
Level 2	Earth Level (Rock & Mud Puzzles)	The Magma & Terran Crucible: Petrified roots of pre-human gargoyles and living crystalline formations that pulse with chthonic energy. Use Gorgon/Cockatrice petrification mechanics.
Level 3	Fire Level (The Chessboard)	The Solar / Plasma Matrix: A deadly grid chamber powered by an trapped, dying star fragment (an ancient Hyperborean power core). Replace chess pieces with automaton guards, Mi-Go constructs, or clockwork brass guardians.
Level 4	Water Level (Drowning / Aquatics)	The Submerged Abyssal Depths: Murky, pitch-black water infused with eldritch slime. Submerged shoggoth-spawn or Deep One hybrid guardians lurk in the dark.

Converting Key Monsters

Most monsters convert directly to Hyperborea baseline stats, but aesthetic tweaks enhance the pulp-horror vibe:

• Shadows / Spectres: Re-skin as Ethereal Phantasms or shadow-creatures spawned from the dream-realms beyond the pole.

• Bugbears / Gnolls (Guardians): Re-skin as Ab-Human Kra'Ki (Pictish tribesmen), Keltish raiders, or mutagenically warped True Human cultists bound to the tower.

• Iron Golem / Automatons: Re-skin as Hyperborean Metal-Constructs or Atlantean Clockwork Horrors powered by crystal batteries.

• The Soul Gem: Treat as a legendary artifact. Anyone attempting to touch it bare-handed must make a Save vs. Death at -2 or have their soul ripped into the gem, turning their body into an empty, violent husk.

Referee Prep Checklist for Hyperborea

1. Cross-Section Map: Draw a simple vertical diagram showing the gravity shifts between the Void, Crucible, Solar, and Abyssal levels.

2. Hazard Tracker: Track light sources strictly—the weird lighting in the tower often distorts non-magical flames, turning torchlight purple or green.

3. Pulp Atmosphere: Emphasize ancient alien metals (electrum, strange alloys), cold stone, and the hum of ancient hyper-technology alongside medieval steel.

OSR Adventure Commentary- Dark Tower By Paul (now Jennell) Jaquays 1979. Levels 7-11 Adapted To Castles & Crusades rpg campaign

Dark Tower (1979) by Paul (now Jennell) Jaquays is widely considered one of the "holy grails" of old-school dungeon design. Originally published by Judges Guild for AD&D, it earned a legendary reputation for its complex verticality, non-linear exploration, and faction-based gameplay.

For Castles & Crusades (C&C) players, the module is a natural fit because C&C is designed to be mechanically compatible with early editions. Here is a breakdown of the module and its specific presence in the C&C ecosystem.

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1. The Core Narrative

The adventure centers on a centuries-old "Cold War" between two gods: Mitra (the god of Law/Sun) and Set (the god of Evil/Serpents).

• The Setting: The village of Mitra’s Fist sits atop a buried mountain pass. Unbeknownst to most, two massive towers—one white (Mitra) and one black (Set)—were buried during a divine cataclysm and now exist entirely underground.

• The Hook: The villagers are cursed with immortality but live in a state of stagnant decay, secretly ruled by a cult of Set.

• The Goal: Players must navigate the social web of the village, delve into the four levels of the dungeon, and eventually infiltrate the towers to break the stalemate or claim the relics within.

2. Why it’s Famous: "Jaquaying the Dungeon"

The term "Jaquaying" (coined by The Alexandrian) refers to the design techniques pioneered in this module:

• Non-Linearity: There are multiple entrances to the dungeon and numerous "loops" and secret paths between levels.

• Verticality: You don't just go "down"; you climb up into buried towers from the bottom of the dungeon or rappel down shafts that skip levels entirely.

• Faction Play: The dungeon isn't a static collection of monsters. The followers of Set and the remnants of Mitra’s clergy are in active conflict. Players can pick sides, play them against each other, or try to kill everyone.

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3. Castles & Crusades Specifics

While the original 1979 printing was for AD&D, Goodman Games released a dedicated Castles & Crusades conversion in the mid-2000s.

Feature	Details
System	Specifically tuned for the Siege Engine (C&C).
Character Level	Designed for a party of 6–10 characters of Levels 7–11. It is high-lethality.
Format	Usually found as a 72-page book (though modern reprints by Goodman Games often bundle it as a massive multi-volume "Reincarnated" set for 5E/DCC).
Conversion Ease	Because C&C uses the same "six stats" and similar AC/Save math as the original, the 1979 version is playable with minimal adjustment, though the official C&C PDF simplifies the stat blocks.

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4. Key Elements to Watch For

If you are running this in Castles & Crusades, keep an eye on these specific highlights:

• Avvakris the Merchant: The primary antagonist. He is a high-level Priest of Set with a complex family dynamic and a terrifying half-serpent son.

• The Lich Pnessutt: An ancient, powerful undead who resides in the depths and serves as a "boss" tier encounter.

• The Relics: Items like the Eye of Set or the Staff of Mitra are powerful enough to shift the balance of a campaign world, not just a single dungeon.

Pro-Tip for GMs: Use the "Side View" map religiously. Because the towers are nested inside the dungeon levels, players often get confused about where they are vertically. Drawing a cross-section for them (or yourself) is essential to keep the geometry straight.

 Since my  group prefers high-stakes diplomacy over simple door-kicking, Dark Tower becomes a tense "Cold War" thriller. In this module, the environment is a powder keg, and the players are the match.

Here is how to frame the negotiations between the two factions using Castles & Crusades mechanics.

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1. The Factions: Goals & Leverage

Faction	Primary Leader	Motivation	Negotiation Leverage
The Chosen of Set	Avvakris (High Priest/Merchant)	Complete the corruption of the village and fully awaken the Black Tower.	They have the numbers, the wealth, and control of the village’s food/water.
The Remnants of Mitra	The White Druids (hidden)	Purge the evil and restore the sun's light to the "Fist."	They have ancient knowledge of the towers' secret paths and the location of the relics.

2. The Village of Mitra’s Fist

This is where the negotiation begins. The village is ostensibly "lawful," but the Cult of Set has infiltrated every level of government.

• The Hook: Avvakris will likely try to hire the players first. He wants them to "clear out" the pesky "heretics" (Mitra’s followers) in the dungeon.

• The Twist: If the players find the secret shrine of Mitra first, the Druids will beg for help, offering divine boons or knowledge of the Staff of Mitra—the only thing that can truly banish Set’s influence.

3. Key Players for Negotiation

• Avvakris: He is a master manipulator. In C&C, he will likely use high Charisma (Prime) checks to win over the party. He doesn't want to fight; he wants to own the party's services.

• Habbakuk: A prisoner who can be rescued. He serves as the moral compass and a bridge to the Mitra faction.

• The "Grey" Elements: There are several monsters and minor NPCs who hate both sides. A clever party can recruit these outliers to create a "Third Way" or to provide a distraction while they play the two main factions against each other.

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4. Running the Diplomacy in C&C

The Siege Engine makes these social encounters dynamic. Use Charisma as the primary attribute for these interactions:

• The Double Agent Play: If a player wants to pretend to join Set while secretly helping Mitra, have them roll a Charisma (Deception) check against Avvakris’s Challenge Class (CC).

  • Note: Since Avvakris is high-level (roughly Level 10), his CC will be high (10 + his level = 20), making it a difficult feat for lower-level PCs.

• The Peace Treaty: If the players try to broker a literal truce (unlikely but possible), they would need to prove that a third threat (like the Lich Pnessutt) is a bigger danger to both than they are to each other.

5. Moral Complexity

Jaquays designed the "Good" faction (Mitra) to be somewhat weakened, dogmatic, and desperate, while the "Evil" faction (Set) is charismatic, organized, and wealthy.

• The Dilemma: Helping Mitra is "right," but it is the harder path. Working for Set is easy and profitable, but it involves committing (or ignoring) atrocities.

GM Tip: Award XP not just for monsters killed, but for Information Secured and Alliances Formed. If they successfully trick Avvakris into revealing the location of the Eye of Set without a fight, give them the equivalent XP of defeating his personal guard.

 

Kingdoms of the Living, the Slimy, & the Dead - - Clark Aston Smith's The Charnal God & Maximum Mayhem Dungeons - Mini Adventure #2: Slime Pits of the Sewer Witch

 It's been a long while since I've done anthing with our Clark Ashton Smith Zothique Castles & Crusades campaign. A friend and fellow player wants together together over the weekend & pick up with our Zothique campaign in a minor kingdom around the region of Zul-Bha-Sair. We've definitely had our times around that region wayback in January of 2024.  My friend Mark Taormino has a new Kickstarter for his OSR imprint Dark Wizard Games. And I'm thinking of incorporating Mark's Dark Wizard Adventure Slime Pits of the Sewer Witch our Clark Ashton Smith's Zothique Castles & Crusades campaign. Here's how we do it. 

Rodney Mathews artwork used without permission 

""Take heed lest you utter blasphemy," admonished the innkeeper. "Mordiggian is old and omnipotent as death. He was worshipped in former continents, before the lifting of Zothique from out the sea. Through him, we are saved from corruption and the worm. Even as the people of other places devote their dead to the consuming flame, so we of Zul-Bha-Sair deliver ours to the god. Awful is the fane, a place of terror and obscure shadow untrod by the sun, into which the dead are borne by his priests and are laid on a vast table of stone to await his coming from the nether vault in which he dwells. No living men, other than the priests, have ever beheld him; and the faces of the priests are hidden behind masks of silver, and even their hands are shrouded, that men may not gaze on them that have seen Mordiggian.""  The Carnel God By Clark Ashton Smith 

So right off the bat the town of Sudengrove becomes a smaller kingdom of  Zul-Bha-Sair. And here's where the addenture plot thickens; 

" The small town of Sudengrove has a big problem: something lurking in the underground sewers has been causing the disappearance of many men, women, and even children during the night! The locals have assembled a team of heroes to venture into the treacherous Slime Pits to unravel the mysteries, deadly traps, and the nefarious plans of the foul creatures that hide within. Lurking deep within the murky labyrinth, your ultimate challenge awaits: a battle against the malevolent sewer witch herself, Hagatha Toadsludge! Filthy riches await those who dare to challenge and survive the Slime Pits of the Sewer Witch!"

The issue is going to arrise with  Hagatha Toadsludge & her victims because while the Ghoul god cares not whose killed. The dead literally belong to him and undead are an abomination to the cult of Mordiggian. Undead sure are tasty! Technically the PC's could be hired by the temples of Mordiggian to clear out the Sewer  Witch. The Sewer Witch might be tolerated for a time until the cult has had it with people going missings. 
Preadventures involving the Sewer Witch might have her moving into the area bringing goblin minions with her. The PC's get hired by a town or the temple to clear her out. She seems destroyed only to move bases into a nearby area. When we reach the events of Mini adventure #2 she's violated the covenant between the humans and the Greater Ghouls by experimenting on the local populace. This comes on the heels of increasing goblin attacks in the area

This opens the adventurers to the events of Mini adventure two when the PC's come face to face with the Sewer Witch's experiments and the weirdness surround them. 
Then things get much more dire as the PC's get thier noses deep with the affairs of the Sewer Witch. And then things are going to go from bad to worse. Maximum Mayhem Dungeons - Mini Adventure #2: Slime Pits of the Sewer Witch is going to pick right up from the events of the pre adventure meeting with the Slime Witch and then all Hell is going to break loose.  You can support the Kickstarter right here.