How it works
A middle-depth look at the rules that actually run, and a clear line between what is explicitly implemented and what may or may not emerge from it.
Organisms
Each organism is a small, distinct entity with a position, an energy level, a health value, an age and a lineage. It carries a compact neural network that maps what it can sense to what it does next.
Sensing
Organisms perceive a limited, local slice of the world: nearby terrain, nearby objects, nearby other organisms, and a few internal signals such as their own energy. They do not have global knowledge of the map or of other organisms elsewhere in it.
Neural controllers
Each organism's decisions come from a small neural network, not a hand-written behaviour tree. The network's connection weights are the product of evolution: they are inherited, mutated across generations, and occasionally adjusted within an individual's own lifetime as it encounters consequences of its own actions (lifetime plasticity, covered further in the science page).
Movement, energy and eating
Moving, acting and simply staying alive cost energy. Organisms recover energy by eating: consuming plant matter or other available food sources in the world. An organism that cannot find enough energy weakens and, eventually, dies.
Reproduction and mutation
Organisms with sufficient energy can reproduce, passing a mutated copy of their neural network to offspring. Mutation is small and random. Selection is not: whichever variants happen to survive and reproduce more successfully become more common over time.
Lifetime plasticity
Beyond inherited, generational change, an individual organism's own controller can adjust somewhat during its lifetime in response to what happens to it. This is a real, implemented mechanism, distinct from evolutionary change across generations, and it is documented separately in the science page.
Materials and the environment
The world contains material: plant matter, wood, stone and other objects that organisms can pick up, carry, drop or otherwise manipulate. Manipulating material changes the world's physical state, and that change can persist long after the organism that caused it has died.
Manipulation, and reshaping the ground itself
Organisms can move loose objects, and under the rulesets the public universes run they can also excavate, carry and deposit conserved units of ground substrate: take a unit from an exposed cell in front of them, hold it while they walk, and put it down elsewhere. Matter is conserved exactly - nothing appears anywhere without being taken from somewhere else - so filling in shallow water somewhere always means digging land down somewhere else. There is no build action and no reward for shaping anything; organisms are simply able to do it. See Reshaping the World for how the mechanism actually works, and whether it has produced anything worth calling a strategy (see research notes).
Weather, day and night, and fire
The world has a real diurnal cycle driving ambient temperature, and a day/night presentation that follows it. Fire can start and spread under the right conditions and interacts with material and organisms in the world. These are authoritative physical processes, not decoration.
Persistent traces, and ecological recovery
Ground clutter, charred material, remains and altered terrain do not automatically clean themselves up. What has happened in a place tends to still be legible there afterwards. Freshly disturbed ground is the exception in one respect: it does not stay a bare scar forever. Ecological succession lets suitable disturbed land recover living cover over time, even while the physical shape it was left in - a terrace, a filled channel, a cut bank - persists in the world's own state.
Lineages
Every organism's ancestry is tracked back to its founders. This makes it possible to say, honestly, which populations a given organism descends from, when a lineage diverged, and when one goes extinct.
What is implemented, and what is not claimed
Everything above is an explicitly implemented rule. Higher-level behaviours you might read about elsewhere on this site, such as whether organisms coordinate, avoid danger cleverly, or exploit the environment in sophisticated ways, are not rules. They are, at most, patterns that may or may not appear as a consequence of the rules above interacting over time. See claim discipline for how this site distinguishes the two.
Going deeper
This page describes the mechanics in plain terms. If you want the actual implementation, with the real dimensions, formulas, parameter ranges and experimental evidence, the technical layer covers the same ground in full:
- The evolving neural controller, the network every organism carries.
- How organisms perceive and act, all 53 sensory channels and all 8 actions.
- Genome, inheritance and mutation, every gene and what it costs.
- Energy, metabolism and death, the itemised cost of a tick.
- Reshaping the world, the conserved substrate organisms can excavate, carry and deposit.
- Everything else.