Substrata

Substrata is a solo journaling RPG about descent—slow, grinding, and half-lit—into the subterranean guts of a city that long ago abandoned its own skeleton. The levels beneath the streets have become a kind of civic oubliette: a necropolis of signage, pipes, drowned echoes, and the stray survivors who cling to them.

You play a Custodian, though the title has outlived its duties. You are trapped in the muttering strata of the Parking complex, where memory condenses on concrete like sweat and every corridor seems to tilt toward some unspoken gravity. There is no GM. No narrator but you. No truth but what you write. You are the last archivist of your own ordeal.

Each day you venture deeper or wait for the place to breathe around you. Each day you document its shifts, its threats, its impossible geometry. Each day you try not to unravel.

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The Original Sin: A Concrete Lung

This solo journaling RPG casts you as the Custodian, trapped in a multi-level, reinforced concrete car park—a massive, brutalist machine sealed by a silent, external collapse. Your only mission is to shepherd a small, fractious group of survivors, the Unselected, to safety.

The game's originality stems from two core pillars:

• Systemic Horror: We reject grand, cinematic chaos. Instead, the dread comes from the terminal gravity of the setting—the constant fight against water ingress, structural spalling, and failing ventilation systems. The true horror lies in your realization that the geometry of the building itself is actively trying to kill you.
• Social vs. Physical Health: The central mechanic is the Cohesion Index (IC). This index measures the social atmosphere of your group, not your personal life bar. You can be the most capable survivalist, but if the IC collapses due to infighting, betrayal, or poor management, you lose. 

Two Modes of Descent

To offer a versatile and terrifying experience, the game is presented in two distinct modes.

1. The Core Protocol (Approx. 7-10 Sessions/8-12 Hours)

This is the standard experience, focusing primarily on the management of the Cohesion Index (IC), the Unselected PNJs, and the fundamental challenges of the Parking. It provides a clean, focused narrative track leading through the four main chapters and the eventual Emergency Aperture Sequence (EAS) Epilogue. This mode emphasizes the social maneuvering required to win.

2. Advanced Substrata: Terminal Density (Approx. 12-16 Sessions/15-20+ Hours)

For those seeking the full, oppressive weight of the Substrata, this mode layers on optional mechanics from Chapter V. Implementing these rules transforms the experience.

• Structural Decay: The environment becomes an active antagonist, imposing random, measurable conditions that you must resolve to prevent resource drains.
• Bureaucratic Failure: Key objectives are obscured by dense, misleading documentation, forcing you to use your Forgotten Profession and sharp intellect to decrypt crucial information.
• The Final Indictment: Your initial Social Scar is integrated into the Epilogues, ensuring your personal trauma defines your final reckoning.

Substrata is a game about facing consequences. We ask you to embrace the complexity, confront the terminal chaos, and journal every minute detail of your descent into the concrete abyss.