OSR Commentary - Overview and Look At Interbellum Red Rpg published by The Red Room

 Interbellum is a tabletop roleplaying game published by The Red Room, heavily rooted in the OSR (Old School Renaissance) style of play. It was originally launched as Wretched Interbellum in late 2023 and later updated and re-released simply as Interbellum in June 2026.

Here is a detailed breakdown of the game's setting, themes, and mechanics:

1. The Setting and Atmosphere

The game is set during the turbulent interwar period between 1914 and 1939, bridging the gap between the end of the Great War and the dawn of World War II.

• Historical Realism Meets Pulp Adventure: Characters travel through real-world locations like the canals of Venice, the streets of Shanghai, the deserts of North Africa, and the remote islands of the Pacific. The backdrop is defined by fragile peace, crumbling empires, colonial expansion, and economic instability.

• Cosmic Horror and the Occult: Beneath the historical veneer lies a dark, supernatural underworld. The bloodshed of the trenches has stirred ancient, forgotten gods and cosmic forces. Secret societies, occult cabals, and corrupt entities pull strings from behind university lecture halls and government ministries.

2. Character Archetypes and Tone

True to the broader "Wretchedverse" designed by The Red Room, Interbellum eschews traditional squeaky-clean heroes for gritty, morally complex protagonists. Players can portray a variety of era-appropriate figures:

• Explorers, archaeologists, and scholars hunting for lost artifacts.

• Aviators, mercenaries, spies, and hard-boiled journalists.

• Occultists, criminals, and revolutionaries caught up in ideological wars.

The tone is heavily inspired by the cynical realism of Ernest Hemingway and Dashiell Hammett, the comic book adventures of Corto Maltese (by Hugo Pratt), and the classic weird fiction/cosmic horror of H.P. Lovecraft. Characters are defined by their personal codes of honor rather than standard alignments, making survival and navigating shifting political factions central to the experience.

3. Rules and Mechanics

Interbellum runs on The Wretched RPG system.

• d20 / OSR Compatibility: The mechanics are heavily d20-based and directly compatible with classic Old School Renaissance systems. This means rules are relatively light, fast-paced, and focus on high-stakes, lethal combat.

• The "Sin" Engine: A signature mechanic of the Wretched system requires characters to embody or personify particular flaws or vices—such as greed, pride, or lust—which directly tie into how they gain mechanical advantages or trigger personal complications during play.

• Sandbox & Random Tables: The book relies heavily on modular sandbox play, offering an extensive collection of historical backgrounds, plot hooks, and randomized tables to generate quick espionage operations, archaeological expeditions, or supernatural encounters on the fly.

4. Availability and Editions

• Wretched Interbellum (2023): The initial 396-page release featured heavy cross-compatibility with the Wretched system.

• Interbellum (2026): A streamlined standalone edition released in mid-2026. It features new cover and interior art (replacing earlier AI-generated assets with human illustrations), rule clarifications, and slightly shifted content to support both traditional pulp-adventure heroes and its legacy of morally ambiguous anti-heroes.

It is currently distributed digitally through storefronts like itch.io and via Print-on-Demand (PoD) platforms like Lulu and Amazon.

Using Interbellum to build adventures means leaning heavily into its specific blend of grit, geopolitics, and cosmic dread. Because it runs on an OSR framework, your preparation should focus on creating a modular sandbox rather than a rigid story script.

Here is how to effectively use the game's tools and themes to construct an adventure:

1. Establish the Historical Catalyst (The Hook)

Every Interbellum adventure should start with a real-world, historical flashpoint between 1918 and 1939. This provides immediate grounding and stakes.

• The Political Friction: Use the rise of extremist factions, colonial uprisings, or corporate greed. A strike at a British-owned rubber plantation in Malaya, a secret meeting of the Weimar Republic’s industrialists, or an illegal shipment of arms through the port of Marseille.

• The Occult Catalyst: Tie the historical event to something supernatural. The bloodshed of the Great War cracked the walls of reality; now, someone is exploiting it. That rubber plantation is built over a sunken temple to a forgotten entity. The German industrialists are funding an expedition to find a prehistoric artifact in the Antarctic.

2. Map Out the Factions (The Sandbox)

Instead of a linear sequence of events, design three or four competing groups who all want the same thing. Let the players drop into the middle of this web. For an Interbellum campaign, a classic faction setup looks like this:

• The Institutional Power: A government agency, military unit, or corporate entity (e.g., the British Secret Intelligence Service, or a French colonial governor). They want control, stability, and resources.

• The Ideologues: Fascists, communists, or anti-colonial revolutionaries. They want to disrupt the status quo, often willing to use forbidden means to achieve victory.

• The Esoteric Cabal: A cult, a secret society of scholars, or a rogue occultist. They understand the supernatural threat and either want to harness it or destroy it at all costs.

3. Leverage the Sandbox and Random Tables

The core rulebook is packed with d100 and d20 tables specifically designed to take the weight off your prep. When building the adventure’s spine, roll on or select from:

• The Espionage & Travel Tables: To quickly generate safehouses, border checkpoints, forged document requirements, and complications during long-distance transit (like a sabotaged train engine on the Orient Express).

• The Rumor Mill: Give the players 2–3 competing rumors when they arrive at a location (e.g., a smoky cabaret in Berlin or an archaeological dig in Egypt). Make one entirely true, one a dangerous half-truth, and one a trap set by a hostile faction.

4. Structure Around High Lethality and "Sin"

Because the system is OSR-adjacent, combat is incredibly dangerous. Design encounters where a straight-up gunfight is usually a terrible idea.

• Leverage Character Flaws: Look at your players' chosen "Sins" (the core Wretched engine mechanic). If a character has Greed or Pride, deliberately place an item or a social situation in the adventure that baits that flaw. Use their vices to complicate the mission.

• Incorporate Clues over Clean Combat: If the players are hunting a cosmic horror in the ruins of a Mesoamerican temple, do not just place it at the end of a dungeon to be fought. Provide journals, dead expeditions, and local folklore that teach the players its specific weakness or how to banish it.

A Sample Adventure Framework: The Weimar Horizon

If you need a quick framework to start running immediately, you can adapt this structure:

Adventure Phase	Component	Details
The Hook	The Assignment	A wealthy degenerate art collector in Munich hires the party to recover a lost manuscript written by a mad medieval monk, recently uncovered during an excavation in the Black Forest.
The Complication	The Rivals	A paramilitary occult group (The Thule Society) wants the manuscript to locate a "thin place" in the forest. Meanwhile, a local communist cell believes the excavation is hiding a secret government weapons cache.
The Investigation	The Urban Crawl	The players must navigate back-alley deals, avoid local police, and infiltrate a heavily guarded manor house where the manuscript is temporarily held.
The Climax	The Cosmic Break	The ritual is already underway in the deep woods. The sky bleeds an unnatural color, and the players must decide whether to steal the book for their paycheck, join a faction, or use dynamite to blow the ritual site to kingdom come.