Iron Meridian: The Great Filter game concept design available for anyone interested.
Hey everyone. I had an idea for a survival-horror/geopolitical simulator and would love to get your feed back. Also up for grabs.
The game is Iron Meridian: The Great Filter. It is a dieselpunk cosmic-horror set in an alternate 1939. Humanity’s early space program has collided with an alien predator ecosystem and the biological wreckage of dissolved future timelines.
Here is the breakdown of the core mechanics, loops, and how I am managing the scope.
1. The "Nested Scope" Architecture
To keep this manageable as an indie project, the game relies on a "Nested Scope" structure. It does not start as a massive open-world game.
Act I (The Ship): Pure, claustrophobic survival horror. You are trapped on a dying colony ship. Inspiration: Alien: Isolation, Directive 8020.
Act II (The Solar System): You secure a ship and break orbit. The UI expands, unlocking a star-map. Mechanics shift to ship management, exploration, and scaling horror.
Act III (The Open Galaxy): The scope pulls back fully into a geopolitical arms race spanning Earth, orbit, and deep space.
By tying the scope expansion to narrative acts, the core mechanics are built in tightly controlled, isolated environments before scaling up.
2. The Biophagic Bridge & Social Mimicry Engine
The anomaly connecting 1939 to modern, parallel timelines is a wormhole stabilized by strange matter. It digests biology to sustain itself. Inorganic tech from 2012+ timelines survives the transit; the crews do not. They are mutated into "Mimics"—the bridge's antibodies.
This drives the Social Mimicry Engine, which operates on two tiers:
Tier 1: Weak Infiltrator. Replaces a crew member and attempts to learn their routine. The horror comes from anomaly detection. You must spot micro-stutters in dialogue or deviations in daily routines (e.g., forgetting to check a reactor gauge).
Tier 2: The Alpha. If an infiltrator survives undetected, or if a crisis occurs, it sheds its disguise and hunts openly.
The Paranoia Loop: Predators use intimate knowledge (drawn from the consumed crewmate) to lower your guard. A hidden "Trust Meter" tracks NPC relationships. If you execute a friendly crewmate out of paranoia, the surviving crew’s "Grit" decays, risking mutinies.
3. The 4-Tier Arsenal & The "Analog Advantage"
Weaponry in Iron Meridian is a narrative device and a survival choice. High-tech shields are tuned for plasma, making them useless against high-velocity 1939 lead. Alien signals can hack smart-targeting systems, but you cannot hack a Vickers gun.
Tier Category Example Weapons Mechanic / Rule
1 1939 Baseline Mausers, Trench Shotguns EMP/Hack-immune. The ultimate, reliable fallback.
2 Echo-Tech M4s, Night-Vision Recovered from future ghost ships. Finite ammo; cannot be crafted.
3 Wunderwaffen Tesla Cannons, Microwaves Nazi tech. Highly unstable, clunky, and dangerous.
4 Alien Biomech Neural-Interface Plasma Triggers an RNG roll: devastating damage OR the weapon feeds on your vitals.
- The Butterfly Effect: Tech Leaks & Arms Races
Every bullet fired in the wrong place rewrites history. There is a Geopolitical Feedback Loop connecting space exploration to the terrestrial 1939 war.
The Witness System: If you use 2012+ Echo-Tech in a skirmish and a Nazi radio operator escapes, their "Research Meter" increases. Within weeks, enemy Jagdkommando units will spawn with crude, vacuum-tube versions of your modern gear.
Sabotage: You can deliberately "lose" a damaged alien weapon, tricking enemy scientists into arming elite guards with guns that have a 20% chance to misfire and explode.
Moral Choices: Handing future tech to the Allies shortens WWII, but accelerates humanity toward a dystopian, hyper-militarized endgame.
5. "The Threshold" (Mutation & Cinematic Consequences)
Relying on Alien Biomech weapons accumulates an Exposure rating. Extended use literally restructures your character's biology. When Exposure crosses a critical threshold, you do not get a standard "Game Over" screen. You get a contextual, Batman: Arkham-style cinematic death based on your location:
Aboard your ship: Your crew realizes you are turning. Your First Officer orders the bulkhead sealed, and your own gunner puts you down.
Nazi Territory: You are trapped in an airlock. An SS scientist takes notes through the glass as the room is vented.
Deep Space: You mutate fully, only to realize you are not the apex predator. Larger alien threats immediately consume you.
This is a permanent consequence, narratively earned by the player's greed for using overpowered alien tech.
6. Art Direction & Perspective Horror
Iron Meridian relies heavily on a contrast between the gritty, grounded nature of WWII and the incomprehensible vastness of cosmic horror.
Aesthetics: Thermal-ablative space zeppelins fueled by hydrogen-hydrazine. Brass levers, analog pressure gauges, and mechanical sextants. Zero digital screens.
Audio Contrast: Earth combat is bass-heavy, muffled, and chaotic (Saving Private Ryan). Space horror is sharp, metallic, and empty, dominated by the rhythmic thump-hiss of your 1939 oxygen recycler.
FOV Mechanics: In "Horror Zones," the game locks to a tight First-Person perspective to restrict peripheral vision. In "War Zones," Third-Person is unlocked. Attempting to use Third-Person in a Horror Zone will glitch the camera, revealing a Mimic standing directly behind you that your character cannot see.
Synopsis
You are a field operative running brass-fitted pressure suits into a galaxy that finished with humanity long before we learned to leave the atmosphere. Your weapons of choice are a Mauser that alien signals cannot hack and a trench shotgun that does not need a firmware update. The future technology scattered across the ghost ships is powerful, finite, and costs you your humanity every time you use it.
The Great Filter is not an event. It is a threshold. Find out if humanity deserves to cross it, and watch very carefully what you are becoming on the way.
Hope you like it.