Combining Warriors of the Red Planet and 13 Parsercs Rpg - The Barsoomian Way

Integrating Warriors of the Red Planet with Thirteen Parsecs (often referred to as 13P) is a very natural fit, as both games are rooted in the "Old School" design philosophy.

While they use different core engines, their shared DNA makes them highly compatible for a "Sword & Planet" campaign.

System Compatibility

• Engine Foundations: Warriors of the Red Planet is a traditional OSR (Old School Revival) game based on the original fantasy RPG rules. Thirteen Parsecs uses the O.G.R.E.S. engine (Old-school Generic Roleplaying Engine System).

• The "Feel": Both systems prioritize high adventure, ruling-over-rules, and a lean mechanical footprint. Because Thirteen Parsecs is designed to be a "New Class of Old School," it shares the same bounded accuracy and power scales as Warriors of the Red Planet.

How to Play Them Together

Since Thirteen Parsecs is a toolkit for any sci-fi subgenre, you can use it to "crunch up" the more minimalist Warriors setting:

• Character Archetypes: You can easily swap classes. For example, use the Mystic Knight or Psychic from 13P to replace or augment the Mentalist in Warriors.

• Starship & Tech Rules: Warriors is lighter on technical vehicle rules. You can use the robust Starship Creation and Combat rules from Thirteen Parsecs to handle the high-flying airships of Mars or Venus without breaking the math.

• Conversion: Since both use standard attributes (Strength, Dexterity, etc.) and similar Armor Class/Target Number logic, you can usually port monsters and NPCs between them with zero math. If a Martian creature in Warriors has a 4 HD (Hit Dice), it will function effectively as a Level 4 threat in 13P.

Why Combine Them?

If you find the "Original Fantasy" bones of Warriors a bit too restrictive for high-tech encounters, Thirteen Parsecs provides the Skill System and Career Training that can give your planetary heroes more specialized utility outside of combat.

Since both games are built on the foundational "Old School" six-attribute chassis, you can port characters with almost zero math. The primary goal is to map the flavor of Warriors of the Red Planet (WRP) onto the slightly more granular 13 Parsecs (13P) engine.

1. Attribute Mapping

Both systems use the standard range (3-18). You can port your Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma directly.

• Saving Throws: 13P uses a unified "Save" based on the O.G.R.E.S. engine. Use the character's Level + Attribute Modifier to hit a Target Number (usually 15 for difficult tasks).

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2. Class Conversion Table

Because 13P is a toolkit, you can "build" a WRP class using its archetypes and career paths.

WRP Class	13P Archetype	Suggested 13P Career
Fighting Man	Soldier	Mercenary or Gladiator
Scoundrel	Operative	Smuggler or Scout
Scientist	Technician	Engineer or Medic
Mentalist	Psychic	Mystic or Telepath

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3. Integrating Features

To make the character feel truly "Red Planet" while using 13P rules, apply these three mechanical tweaks:

• The "Barsoomian" Perk: Every character from WRP should receive a +1 bonus to all Athletics and Leaping checks in 13P to represent the lower gravity of a dying world.

• Weapon Scaling: Use 13P's weapon damage (e.g., 1d6 for light, 1d8 for medium). Treat WRP Radium Pistols as 13P Blaster Pistols, but keep the WRP "Misfit" rule (exploding on a natural 1) to maintain the high-stakes feel of ancient tech.

• Mentalism vs. Psionics: Use the 13P Strain system for Mentalists. Instead of WRP's "Daily Uses," allow the character to push their powers by taking 1d4 non-lethal damage per level of the effect used beyond their safe limit.

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4. Health and Armor

• Hit Points: You can keep your WRP Hit Points as-is. Both systems scale similarly per level.

• Armor Class: 13P typically uses Ascending AC. If your WRP character has a Descending AC of 5, their 13P Armor Rating is 15.

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