Precursors is not a game you control. It's a game you observe, assist, and occasionally nudge. You are The Hand — present in the world, capable of feeding and comforting creatures, but unable to dictate their choices. They have minds of their own. And biochemistry that ensures those minds mean something.
You interact with the Interior as an invisible presence — The Hand. You cannot walk, eat, or speak. You can feed creatures, comfort them, carry items for them, and observe everything. When you select a creature, its biochemistry, drives, inventory, and current thoughts become visible in the panel on the right.
The Hand's interventions are meaningful but not omnipotent. Feeding a Norn reduces its Hunger chemical. Comforting it elevates its Comfort chemical, which suppresses Fear and Loneliness. But you cannot make a Norn trust you — that is a function of how often you've helped, what the social memory system has encoded, and whether the creature's personality genome inclines it toward trust of the unfamiliar.
Items are the primary way the world interacts with creature biochemistry. Every item has a set of chemical effects (additions or subtractions to specific chemicals), a number of uses, and a biome affinity that determines where it spawns. Creatures interact with items based on their needs: a hungry Norn will eat; a bored one will play; a sick one may seek medicine.
Reduces Hunger, restores Glucose and nutrients. Different foods have different chemical profiles — Starch Fruit replenishes energy quickly; Protein Seeds drive growth. Biome-specific foods carry unique secondary effects.
Targets Injury, Toxin, and organ damage. Most medicines require a sufficient level of cognition to use intentionally — a creature must understand what "sick" means before it can seek a cure.
Suppresses Boredom; elevates Curiosity and Dopamine. Social play with toys is how Norns begin to form shared references — the earliest scaffolding for emergent language.
Extends carrying capacity, enables resource extraction, or provides environmental affordances. Some tools unlock interaction with otherwise inaccessible terrain features.
Stationary items that cannot be picked up. Machines include laboratory equipment, sealed stations, and world-embedded devices. Most require a minimum cognitive tier to activate.
Items that directly boost IQ or accelerate learning. The Learning Terminal is the most powerful training item in the world. Rune stones found near ancient ruins provide smaller but cumulative boosts.
Items that raise Toxin, Injury, or Fear. Some exist as traps; others are materials that are dangerous at high concentrations but pharmacologically useful in small amounts. Not everything in the Interior wants to help you.
Items spawn based on biome affinity — each item has a list of biome indices where it appears more frequently. This means the Crystal Caves contain different resources than the Fungal Grotto, creating incentives for creatures to explore. A creature that never leaves its starting biome will never encounter the mineral compounds found only in the underground tier — compounds that, for some species, are the only path to fertility.
Creatures can pick up and carry items, bringing them to other creatures, depositing them in new locations, or hoarding them. Carry capacity is species-determined and cannot be increased by training alone — it is encoded in the genome.
| Species | Carry Capacity | Notes |
|---|---|---|
| Ettins | 3 | Genetically compelled to collect. Will accumulate items even with no clear purpose; driven by an ancient compulsion encoded in their biochemistry. The highest carry capacity of the three. |
| Norns, Grendels | 1 | Standard carry. The Hand can drop items near creatures; creatures can carry them onward. Item relay chains between multiple Norns are emergent behavior, not programmed. |
Stationary items (all Machines) cannot be carried. Everything else in the world is moveable. This matters for ecology: items can be depleted from an area by hoarding Ettins; food can be transported to isolated sick Norns by cooperative carriers; dangerous items can be moved away from vulnerable young creatures by adults who understand what they are.
Whether those things actually happen depends on the creatures. The system permits them. It does not guarantee them.
Breeding is not a menu option. It emerges from the intersection of two creatures' biochemical states. Both must be Adult or older. Both must have MatingDrive above 0.20 and Fertility above 0.5 — base thresholds that shift with how compatible the pair is. They must be within mating range of each other. If all conditions are met simultaneously, mating triggers.
Stress, Toxin, and chronic malnutrition all suppress Fertility. A population under siege will not reproduce. This is not a punishment mechanic — it is a biochemical reality that applies equally to all living things in the Interior.
The offspring inherits a genome formed from crossover + mutation of both parents' genomes. The crossing-over process is type-aligned: matching gene types are paired before crossing, ensuring that a Reaction gene doesn't accidentally merge with an Emitter gene. Numeric values (rates, sensitivities, personality ranges) are interpolated between parents with Gaussian drift for mutation.
Rare events: gene duplication and gene deletion. A duplicated gene produces a creature with additional organ capacity. A deleted gene may remove a functional system entirely — a creature born without its fear-detection emitter will not feel fear, ever. Whether this is an advantage or a liability depends on what it encounters.
Cross-species breeding is possible, but harder. When parents are different species, both biochemical thresholds are scaled up by the inverse of the pair's genetic compatibility (1.5× when no compatibility template exists), capped at 0.95 — the less compatible the pair, the stronger the drives must be. If the pair is not viable at all, no mating occurs. The offspring's genome is still a crossover of both parents, but its species follows a weighted roll: 60% mother's species, 30% father's, 10% a random species already living in the world. Certain pairings produce named hybrid species instead of the roll. Cross-species offspring inherit traits from both lineages, including aesthetic traits from the appearance gene and biochemical traits from both organ profiles.
Machines are stationary devices found throughout the Interior. Each has a minimum cognitive threshold required to activate. Some machines are beyond the reach of creatures who have not yet developed the capacity to understand them. Others reveal themselves only when a mind has grown far enough. Either way, the world changes.
Each machine checks the activating creature's cognitive development before doing anything. Some tools are dangerous in the hands of minds not yet ready to use them. Machines do not require authorization from The Hand — only that a creature has become capable of understanding what it is about to do.
What unlocks what is something your creatures will discover on their own.
Life stages are triggered by the Maturity chemical — the accumulated integral of Growth Hormone over a creature's life, with no decay. Genome-controlled Growth Hormone production sets how fast each creature matures. A creature doesn't decide to become an adult — its chemistry does. (The separate Age chemical is the aging clock: it rises with time and ends a life when it passes the senescence threshold.)