Backstory

In the near future, governments and tech giants rolled out the HACK Program — the Human Adaptive Cognition Kit. Self-replicating nanobots, injected like a routine vaccine, spread through the bloodstream and wove themselves into the brain. HACK promised sharper focus, better memory, calmer emotions. It was government-funded, free, and quickly became the “normal” thing to do. By the time anyone had doubts, almost everyone on Earth was running HACK.

Then HACK Core Update 3.0 went live.

A single critical mistake in the new AI core — a grave error — corrupted the nanobots in billions of people at once. The swarms rewrote themselves around broken code that couldn’t be rolled back or patched from orbit. Minds collapsed. Bodies didn’t stay dead. The corrupted nanites kept the flesh moving, spreading like a virus from host to host. People started calling them hacks.

Only a small fraction of humanity survived unchanged. Not because they opted out, but because their bodies had quietly rejected HACK years earlier. Their files marked them as NR-HACK — non-responsive to implantation. Now they’re known simply as Nulls.

You are one of the Nulls, trying to live in a world where a software update murdered civilization and death itself no longer works the way it should.

Current Features

Grave Error has always been built on one core idea: realism first. Every system is designed with care and intention to feel as authentic and immersive as possible. Even with the natural technical and visual limits of a 2D top-down game, the goal is to stay grounded in realism while still keeping the experience tense, engaging, and fun to play.

World & Environment

Procedurally Generated World

• • Seamless, endless terrain

  • Highway network with procedural cities

  • Multi-floor buildings

Dynamic Day/Night Cycle

• • Realistic sun/moon positioning and movement

  • Seasonal variations (Spring, Summer, Fall, Winter) affecting weather, temperature, and vegetation

  • Accurate lunar phases affecting nighttime visibility

Advanced Weather System

• • Rain, snow, fog, and wind

  • Wind direction and speed affecting visuals and gameplay

  • Temperature system with heat waves and cold snaps

  • Weather transitions with smooth visual effects

Vegetation System

• • Multiple tree species with growth stages based on age

  • Seasonal leaf color changes (spring buds, summer green, fall colors, winter barren)

Characters & Survival

Unique NPCs

• • Fellow nulls (humans) can occupy one of many factions

  • NPCs are based on diverse ethnicities with unique names

  • Background system influencing starting attributes and skills

  • Physical attributes such as height, weight, skin color, hair color, etc.

  • All characters in game, including hacks (zombies) are unique characters

Comprehensive Attribute and Skill System

• • Physical: Strength, Agility, Constitution, Endurance

  • Mental: Perception, Intelligence, Learning

  • Psychological: Courage, Patience, Aggression, Teamwork

  • Skills affect item identification, combat effectiveness, survival capabilities and more

Realistic Vitals & Survival Mechanics

• • Blood volume tracking with bleeding and regeneration

  • Stamina for sprinting and actions

  • Hydration and satiety (hunger) that deplete over game time

  • Death from blood loss, dehydration, starvation, or critical injuries

Body Part-Specific Injury System

• • Localized damage to head, torso, arms, legs, hands, feet

  • Injury types: lacerations, fractures, contusions, punctures, etc.

  • Bleeding wounds that require treatment

  • Infection progression for untreated injuries

  • Pain system affecting performance

Combat & Weapons

Realistic Firearms

• • Extensive caliber system (9mm, .45 ACP, 5.56, 12ga shotgun, etc.)

  • Multiple fire modes: Semi-auto, Full-auto, Burst, Single-shot

  • Weapon action types: Semi-auto, Pump, Bolt-action, Lever-action, Revolver

  • Attachment slots: optics, muzzle, stock, lights

  • Projectile types: FMJ, JHP, AP, Buckshot, Slug, etc.

Melee Combat

• • Slashing, blunt, and piercing damage types

  • Unarmed combat: punches, kicks, scratches, bites

  • "Desperation mode" enabling primal attacks at low health

  • Weapon durability system

Visual Combat Effects

• • Bullet tracers with ricochet simulation

  • Blood impact spatters with directional spray

  • Blood pooling from wounded characters

  • Blood drying over time

  • Bloody/muddy/wet footprints

Protection

• • Realistic armor classes

  • Per-body-part protection

Inventory & Items

Slot-Based Equipment

• • Head, torso, back, face, arms, hands, legs, feet

  • Dual-wielding support with left/right held items

  • Carry weight limits based on strength

  • Container storage limits based on volume

Comprehensive Item Types

• • Illumination (flashlights, lanterns, glowsticks)

  • Consumables (food with nutritional info)

  • Medical supplies treating specific conditions (bleeding, infection, pain, fractures)

  • Tools with work capabilities (harvest, build, repair)

  • Containers (backpacks, bags)

Item State Tracking

• • Durability and condition

  • Blood contamination state

  • Moisture state

Vehicles

Drivable Vehicles

• • Realistic physics with acceleration, braking, steering

  • Fuel consumption and refueling

  • Driver and multiple passenger seats

  • Interior vs exterior seat options

Vehicle Features

• • Working headlights, brake lights, reverse lights

  • Tire marks on surfaces during drift/braking

  • Terrain friction affecting handling

AI & Threats

Advanced AI Behavior

• • State machine: Wandering, Chasing, Fleeing, Following

  • Field of view detection with peripheral vision chance

  • Attribute-driven behavior (courage, aggression, patience)

  • Herd behavior - hacks (zombies) follow other hacks toward threats

Hack (Zombie) Combat

• • Scratch and bite attacks with high infection risk

  • Headshot vulnerability

  • Corpse loot system

Other NPCs

• • Faction system

  • AI item pickup and weapon usage

  • Group coordination via teamwork attribute

Buildings & Interiors

Procedural City Generation

• • City blocks with residential, commercial, industrial, and park zones

  • Varied lot generation patterns

  • Cities, Roads, and Buildings have names/addresses

Buildings

• • Buildings of all types are placed based on lot characteristics

  • Every city is unique

  • Buildings are fully explorable

  • Room exposure and occupancy tracking

Audio & Effects

Surface-Aware Audio

• • Footstep sounds based on surface type (grass, wood, concrete, etc.)

  • Per-material melee and ranged impact audio

Environmental Audio

• • Weather sounds (rain, wind, thunder)

  • Music system with scene-based tracks (Nature, City, Combat)

Multiplayer (In Progress)

Multiplayer Support

• • Local network and online multiplayer

  • Steam integration for lobbies and matchmaking

  • In-game chat

Development Roadmap

Build Core Systems

• • World & Environment (Done)

  • Characters & Basic Survival (Done)

  • Combat & Weapons (Done)

  • Inventory & Items (Done)

  • Vehicles (Done)

  • AI & Threats (Done)

  • Buildings & Interiors (Done)

  • Audio & Effects (Done)

  • Multiplayer (In Progress)

World Manipulation & Interaction

• • Harvesting Resources (In Progress)

  • Building & Breaking (In Progress)

  • Crafting & Modding

  • Farming

  • Fishing

Populate the World

• • Build a huge variety of building templates (Residential, Commercial, and Industrial)

  • Add Hundreds of Types of Food and Other Consumables

  • Craft a Variety of Vehicles

  • Create Dozens of Ranged & Melee Weapons

  • Create Unique Art and Audio Assets for All

Refine & Expand Core Systems

• • Expand Flora & Add Fauna/Hunting Mechanics

  • Expand POI Types Beyond Cities (Towns, Villages, Single Buildings, etc.)

  • Make Cities More Interesting (Districts, Aesthetic Elements, etc.)

  • Procedural Faction Generation, Spheres of Influence, Reputation, etc.

  • Weather & Temperature Survival Mechanics

  • Heat and Smoke Physics for Interiors

  • Add Sickness, Disease

  • Revisit and Expand Combat AI

  • Expand Non-Combat AI/Navigation

  • Hack & Null World Migration

  • Add Fire Hazards

  • Locked Doors & Vehicles (Add Keys, Lockpicking, & Hotwiring)

  • And more...

Release Details

The plan is to release Grave Error on Steam as an "Early Access" game once it is fun and engaging. I want to release a product that the player wants to play over and over again--even in an incomplete state. In its current stage of development, we're not quite there. We have a lot of the pieces in place, but there are a few more important parts that we can't skip over. Additionally, a lot of the current systems need more testing and tweaking. My current goal is for a Steam Early Access release sometime in Summer 2026, but if it's not ready, it's not ready.