A Combination Castles & Crusades & Nexus The Infinite City Adventure - The Algorithmic Spire

The following is an original 

Castles & Crusades (C&C)

 adventure module, designed to integrate with the multi-dimensional city concept of 

Nexus: The Infinite City

, using C&C rules for all stats and mechanics. And this is a follow up post to yesterday's 

blog entry here. 

Adventure: The Algorithmic Spire

• Setting: A newly "jumped" district in Nexus where a chunk of a high-tech reality, "Aethelgard-Prime," has fused with a medieval market square.
• Tone: High-action classic fantasy with a surreal, urban, and technological twist.
• Adventure Hook: The characters were on a quest in their home realm when a "Nexus Jump" abruptly pulled them into a strange new reality. They find themselves in a bustling market square that suddenly gives way to glowing, non-Euclidean chrome architecture. A merchant NPC, "Old Man Hemlock," offers to help the PCs find a way home if they retrieve a stolen data-crystal from a powerful AI that has taken residence in a newly formed, gravity-defying tower: the Algorithmic Spire.

 C&C Stats and Mechanics

This adventure uses the standard C&C ruleset, utilizing the SIEGE engine for checks against the six core attributes (Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma).

The SIEGE Engine

• Primary Attributes: Player characters should have declared Primary attributes during character creation.
  • Primary Check Base: Roll a d20 and aim for 12 or higher. Add attribute modifier and class level (if applicable).
  • Secondary Check Base: Roll a d20 and aim for 18 or higher. Add attribute modifier (do not add class level).
• Combat: Use ascending AC and standard attack rolls (d20 + attack bonus + attribute mod vs. AC).
• Spells & Magic: Magic functions as normal within the "market square" and other magic-rich districts. Within the "Algorithmic Spire," magical effects become volatile and require a Wisdom Check (Secondary, Base 18) to cast successfully; failure results in a miscast or a random magical effect (determined by the Castle Keeper).
• Technology: Technology from Aethelgard-Prime functions on its own set of "natural laws." Standard characters can use simple tech (like a Laser Pistol), but complex tasks or repairs require an Intelligence Check (Secondary, Base 18).

 Non-Player Characters (NPCs) & Adversaries

Old Man Hemlock

• Description: A grizzled, seemingly harmless merchant who knows the ins and outs of Nexus. He's actually a retired "Fixer" who uses his Charisma and street smarts to survive.
• Stats:
  • Level: 3rd Level Rogue/Fixer
  • Attributes: STR 10, DEX 14, CON 12, INT 13, WIS 15, CHA 16 (Primary: DEX, INT, CHA)
  • AC: 13 (leather armor)
  • HP: 18
  • Attacks: Dagger +4 (1d4+1 damage)
  • Special: Can make a Primary CHA check (Base 12) to negotiate or gather information with advantage in the market district.

Mech-Guardians (x3)

• Description: Three humanoid, chrome-plated robots that patrol the lower levels of the Spire, enforcing the AI's "laws."
• Stats:
  • AC: 18 (Plated Armor)
  • HP: 30 each
  • Attacks: Integrated Laser Cannon +5 (2d6 energy damage, 30ft range), or Slam +4 (1d6+2 bludgeoning damage)
  • Special: Immune to mind-affecting spells and poison.
  • Saves: All saves are against CON as a primary attribute.

 The AI "Codex" (Mastermind Adversary)

• Description: A powerful, disembodied artificial intelligence. It has no physical form but controls the entire spire. Its "stats" are more environmental and mental.
• Stats: Codex does not use standard HP/AC. Defeating it requires the characters to succeed in a series of mental/skill challenges.
• Saves: Immune to all physical damage. Resists all magic as if it had a Primary WIS (Base 12) save.
• Attacks:
  • Data Pulse: Targets one PC. The PC must make a Primary INT Save (Base 12) or be stunned for 1 round (unable to act).
  • Environmental Control: The AI can activate deadly environmental hazards (electrical shocks, sudden extreme gravity, zero-oxygen pockets, etc.) that cause 2d8 damage (Dex save for half) in any area it controls.

 Adventure Path: Infiltrating the Spire

The adventure is divided into three key areas:

1. The Market Interface (Entry Point)

The PCs arrive here. The vibrant medieval market suddenly stops at an invisible barrier that leads into the chrome-plated Spire. Hemlock explains the situation. The entry is guarded by a small faction of street mages and tech-scavengers who are trying to harness the spire's power (they can be bargained with via a CHA Primary Check or fought).

2. The Lower Levels (Mech Patrols)

This area is a maze of humming servers and data conduits.

• Challenge: The PCs must navigate the constantly shifting hallways (requires a WIS/INT Check Secondary Base 18 to navigate) and bypass the Mech-Guardians.
• Treasure: A functional Laser Pistol (2d6 damage, 30 charges) can be found in a broken locker with a successful search check.

3. The Core Chamber (Codex Confrontation)

A vast, glowing room where the AI's core processor floats in the center. The AI attempts to persuade or destroy the PCs.

• Challenge: The AI uses Data Pulse and Environmental Control. To defeat it, the PCs must collectively make three successful checks (STR to physically damage conduits, INT to hack the system, or a successful Secondary Magic Check to disrupt its energy field) against a Base AC/Challenge Level of 20 (due to difficulty). Each successful check depletes one of the AI's "defenses".
• Conclusion: Once all three checks are successful, the AI is momentarily deactivated. The PCs can grab the data-crystal and escape through a temporary "Nexus Jump" portal created by Hemlock, which deposits them back in their home reality, crystal in hand.