Tidepool.life — Evolution Simulator

Tidepool is an artificial life simulator that models evolution from the ground up. You seed a population with starter creatures, set the environment, and then step back while natural selection runs in real time.

Each creature has a physically simulated body shaped by 58 heritable genes, a small neural-network brain that controls all behaviour, and a diploid genome carried on chromosomes — just like real biology. Creatures forage for food, flee predators, find mates, reproduce, and eventually die of old age or starvation.

No two runs play out the same way. Some lineages become sleek water gliders, some evolve into armoured land tanks, some specialise on a single food colour, and many simply go extinct. The simulation combines Mendelian genetics, chromosomal crossover, Gaussian mutation, neuroevolution, body-based movement, and environmental pressure into a living system you can observe, tune, and experiment with.

The world is a 6000 × 6000 unit top-down environment. When you start a run, you choose a habitat type and Tidepool generates the exact island layout from that template.

Water is the default terrain. Creatures spawn and drift in water unless they develop rear-weighted leg-like appendages plus enough body support to walk, or enough tail-assisted slithering ability to move onto land. Islands are solid landmasses — water-only creatures physically bounce off their edges, while creatures that can move on land can cross onto them.

Each habitat still varies from run to run, but the chosen type controls the broad structure. Land and water also have separate food supplies and movement styles, creating different niches for creatures to adapt to.

• Water: Suits streamlined bodies, strong tails, and useful fins or flippers. Larger, bulkier, or heavily limbed creatures can still swim, but they usually need more muscle and better shape to move well.
• Land: Starts with tail-assisted slithering or low crawling, then improves as appendages become better placed, better supported, and more leg-like. Rear appendages provide most walking push, front appendages steer and brace, and long supported limbs can produce longer steps or bounds. Tails can help early shore movers push and slide, but long tails can get in the way once a lineage becomes a mature walker.
• Islands generate their own food independently of the water food supply, creating separate foraging zones and selection pressure.

Every creature is in a constant battle to stay alive. Two resources govern survival: hunger (energy) and stamina.

Hunger acts as the creature's energy store. It starts at full capacity and depletes constantly through metabolism, movement, and brain activity. When hunger hits zero, the creature starves and dies. Plant food refills hunger up to normal capacity; carcasses and hunt remains provide edible body tissue plus the creature's remaining stored energy, while a successful live hunt can briefly push a predator above that cap. Fat provides most reserve capacity, muscle adds a smaller reserve and costs more upkeep, organ tissue stores very little energy, and structural tissue stores none.

Stamina governs burst movement. Every push (thrust) costs stamina, and turning has its own terrain-specific stamina cost. When stamina is depleted, the creature cannot push — it can only coast. Stamina rebuilds over time as the body restores short-term energy. A hungry creature has less usable energy for sprinting, even if its muscles are built for power.

• Energy reserve capacity: How much energy the creature can store. Derived from tissue areas: fat is the main reserve, muscle contributes a smaller usable reserve, organ tissue adds modest storage, and structural tissue adds none.
• Baseline energy use: The baseline cost of staying alive. Active muscle, living tissue, demanding senses, larger brains, jaw strength, and recovery after exertion can all raise it; fat tissue is comparatively low-maintenance.
• Pregnancy adds separate prenatal and offspring-provision energy drains while normal metabolism continues. Male investment time in mate represents protection or provisioning time and lengthens the male's reproductive cooldown, while direct mate energy gifts can still help the mother survive gestation.
• General muscle: Balances raw thrust, stamina strain, recovery, and upkeep.
• Fast-twitch muscle: Gives the strongest raw thrust, but each push spends more stamina and upkeep is a little higher.
• Endurance muscle: Improves repeated-push efficiency and recovery, with lower raw thrust.
• Fast-twitch bodies can surge, but tire harder. Endurance-built bodies recover and repeat effort more easily, but give up some raw thrust.
• Max stamina comes mostly from muscle tissue, with organ tissue supporting that capacity. Stamina recovery comes from muscle tissue, organ support, endurance muscle, and available food reserves. On land, body support, gait, tail-assisted movement, and front-end control shape how quickly movement and turning tire a creature.
• Creatures also die of old age. Lifespan is influenced by body size, reserve tissue, slower energy use, and the creature's derived maturity age, so lineages that take longer to mature usually also gain a longer total lifespan.

Action Dots — Reading Behaviour at a Glance

When Action Dots are enabled, every creature displays a status indicator. The dot shows the current action, colour-coded by drive. Hunger, stamina, and energy remain available in the selected creature panel, along with whether mating intent is active.

Food comes from two sources: plant food that grows in the environment, and carcasses or hunt remains left behind by some creature deaths. Which source a creature can use depends on its diet genes.

Plant food appears as coloured circles on both land and water. Pellet size varies, and larger pellets hold more available plant energy. A creature gets the most from food that shares the same colour channels as its body. Missing a required food colour means no plant energy from that item; weak matching channels give a tiny energy payoff; extra off-colour pigment dilutes the payoff, so bright white generalists are useful but not perfect.

Carcasses and hunt remains are temporary meat resources. Full carcasses can appear when a creature dies from starvation, age, or manual removal; predation kills can leave smaller hunt remains from edible body tissue and leftover reserves the predator did not absorb. Both lose freshness and available meat over time. Once a creature has enough meat digestion and a usable carrion mouth, it can begin with small scavenging bites before becoming a strong scavenger.

Diet is split into plant digestion efficiency and meat digestion efficiency. Each trait needs digestive organs; full mixed diets can express both, but they use more organ space and upkeep. Meat digestion decides how much animal tissue is worth, while live hunting also needs the right mouth shape, jaw strength, bite power, and prey size.

• Plant energy depends on the food's size, colour match, plant digestion efficiency, and how much the creature can handle in a bite.
• Carcass energy depends on remaining meat, freshness, the size of the chunk being eaten, and meat digestion efficiency.
• Mouth fit and mouth size shape bite size, while mouth fit and jaw strength shape chewing and handling time. A creature handles one bite at a time, so chewing any plant, carcass, or prey bite delays the next bite.
• A creature can focus on plant food, carcasses, or live prey. Contact feeding follows that focus, so a creature steering toward one meal type does not automatically bite every other edible thing it touches.
• Plant feeding still needs enough plant digestion, while carcass feeding has a gentler bridge: very low meat digestion allows only tiny nibbles before scavenging becomes worthwhile.
• Inefficient or poorly matched eaters get less energy from the plant or carcass material they bite. Unbitten food remains for later, but a plant that fits inside the bite is consumed.
• Scavenging can support meat-leaning lineages even before they are strong enough to hunt live prey.
• Default food comes in three colours. Land starts red-dominant (Red 60%, Blue 30%, Green 10%), while water starts green-dominant (Green 60%, Red 30%, Blue 10%). You can change these ratios in Simulation Settings.
• Food production can run in Manual or Auto mode separately for land and water. At the start of a run, Tidepool estimates each terrain's plant-food rate from habitat area, balanced creature load, and expected food value. Manual uses that rate exactly unless you change it.
• Max Food is a manual-mode ceiling. Auto mode uses habitat area for the runtime cap, estimates the food flow needed to support a balanced population, and slows production when crowding shows the terrain is carrying too many creatures.
• Water food is periodically dispersed to prevent clumping, simulating currents and drift.

Meat eating has two related strategies: scavenging carcasses or hunt remains and hunting live prey. Scavenging can begin with tiny low-efficiency nibbles, while live hunting appears when a lineage combines enough animal-tissue payoff with real attack tools.

Predators eat living prey through physical bite contact and repeated bite cycles. Mouth size gives physical reach and gape, mouth type decides whether that gape is shaped for plant-food cropping, carrion tearing, or live-prey gripping, and strong jaws add force and visible heft. Strong jaws make live-prey bites hit harder, recover faster, and overcome tougher shells. Prey value comes from the target's current edible tissue and part of its remaining reserves. Carcass ripping is deliberately slower than live hunting recovery, so a successful catch can be a bigger payoff. A hunter that is already over its normal energy reserve capacity cannot keep eating again immediately.

Shells are active defences, not just size labels. A hard shell can stop weak jaws completely. If a predator can crack it, bites damage shell integrity first; only after protection is worn down do body bites become dangerous. Dense bodies also add a little physical toughness. Shell material costs energy to grow and repair, while its weight still affects movement.

• Mouth size: How wide and far the mouth can reach. It helps make contact and handle bulk, but feeding value still depends on diet, mouth type, digestion, jaw strength, and target.
• Mouth type: The feeding shape of the mouth. Plant-cropping mouths bite plant-food items, carrion mouths tear carcasses, and predator mouths grip live prey.
• Jaw Strength: Adds bite force and visible mouth heft. Strong jaws help chew and handle bites, crack shells, improve live-prey bite damage, support carcass ripping, and add tooth cues on meat-adapted mouths. They add a little physical load.
• Meat digestion: Determines how much energy a creature gains from animal tissue. Low usable values support tiny carcass nibbles; higher values make scavenging worthwhile. Hunters also need attack traits such as a predatory mouth, bite damage, jaw strength, and prey-size handling.
• Live cannibalism is blocked — creatures cannot hunt members of their own species or recorded parent species. Carcasses can still be scavenged.
• Defence integrity: The current durability of a shell. In the selected creature panel, defence is shown as current / max so you can see when armour has been damaged.
• Juveniles are often more vulnerable because their body size, bite power, soft-body toughness, and shell protection are still developing.

Reproduction requires finding a compatible opposite-sex mate: usually the same species, one of the creature's recorded parent species for parent-lineage and hybrid-derived creatures, or another hybrid that shares a recorded parent species. Both creatures must be old enough and ready to breed again. The process involves mate signaling, physical contact, pregnancy, and sex-specific energy and time investments.

Creatures broadcast mate signals when their brain decides to. Signals have a radius determined by mate-call volume and body size, and wider signals cost more energy per call. Other nearby compatible opposite-sex creatures can hear those short-lived calls and respond. A call opens the chance to form a match; once a pair is matched, that target can continue after the sound fades, and the match ends when either creature is no longer ready or compatible. The mate-signal system favors preferred, reachable, same-species callers first, then weighs repeated calls and proximity inside distance bands to create mutual attraction.

When two compatible creatures with reproductive intent collide while neither is fleeing, mating occurs. Both parents generate gametes (via crossover and mutation), which combine into the child's genotype. The child's brain genome is bred from both parents' brains. The female becomes pregnant, carrying the developing offspring.

Each pregnancy can plan one or more offspring. The brood-size investment gene feeds linearly into a calculated brood-size target. Larger broods divide the mother's carrying capacity into smaller newborns, prenatal birth energy decides how many can be built and how developed they start, and offspring-care time gives born juveniles a temporary protection window.

• Gestation duration controls when birth happens, how long prenatal costs are spread out, and how far embryos can develop before birth, with a mild reduction for larger broods.
• At birth, prenatal pregnancy energy pays for each newborn's initial body material, minimum reserve, early growth runway, and birth development. If birth energy is short, fewer planned children may be born rather than lowering every child below the minimum viable start.
• Females have baseline prenatal pregnancy provision, and pregnancy energy investment can raise that body-building budget. Extra female provision and male offspring-energy investment become additional reserve for the babies that are actually born.
• Males can also transfer energy directly to their mate. This represents an immediate provisioning gift to the female, shares the male energy-investment budget with offspring provisioning, and helps her survive and fund gestation.
• Gestation sets each child's starting-development ceiling, while the mother's physical brood capacity makes larger broods start smaller and prenatal birth energy pays the actual body-building cost. Female and male offspring-time investment represents care before independence: guarding, feeding, and protection that appears as temporary juvenile protection after birth. These investments create reproductive cooldowns for the investing parent.
• Male offspring-energy investment represents resources directed into the young after birth, such as food, guarded access to food, nesting effort, or carried nutrients. In the simulation this is stored on the pregnancy at mating, then spread across the babies actually born as extra starting reserve.
• High offspring counts create a quantity-over-quality strategy: many smaller children can be planned, but each must still be built from the pregnancy's prenatal energy and underfunded births may produce fewer than planned.
• The Selected Creature Panel's Compatible Mates control filters the simulation view to actual current mate candidates for the inspected creature: living opposite-sex creatures that are adult, ready, not pregnant, and lineage-compatible. Hybrid lineage is included, so a creature may be compatible with hybrid-derived species when a recorded parent species matches.
• Creatures must reach their derived maturity age before first mating. That timing emerges from body size, structural investment, and the maturationTempo gene.

Newborns are not tiny full-strength adults. Each child has an adult genetic blueprint, but only part of that phenotype is expressed at birth and the rest develops over childhood.

Gestation shapes how developed a child can be when it enters the world, within the mother's birth-size limit. Maternal prenatal pregnancy provision pays for the child's starting body material and reserve, while female and male offspring-energy investment can add extra reserve to help it survive the dangerous first part of life.

Childhood length is derived from the creature's adult body size and structural investment, then adjusted by the maturationTempo gene. Larger, more heavily supported creatures tend to mature later unless they evolve a faster maturation tempo, and that slower life-history pace also contributes to a longer lifespan.

Childhood is a dangerous stage. Juveniles are smaller, weaker, less protected, and easier for predators to eat. Shell defence, soft-body toughness, and overall defensive size all grow over time, so a species that is safe as an adult may still be vulnerable when young.

• The pregnancy-duration gene delays birth, spreads prenatal costs over time, and lets embryos develop further before birth. Larger broods mildly lower that development ceiling and split maternal carrying capacity into smaller newborns. The pregnancy-energy-investment gene controls how much prenatal body-building energy the mother tries to pay into that window.
• The female and male offspring-care duration genes simulate parental protection, guarding, feeding, or support before the child is fully on its own. The simulation represents that care as temporary juvenile protection and a longer cooldown before the parent can reproduce again. Female cooldown begins after birth; male cooldown begins at mating.
• Baseline pregnancy provision sets the prenatal birth energy available to the pregnancy. It pays for newborn body material, starting reserves, and early growth runway, while female and male offspring-energy investment adds extra reserve to the babies that are born. With many offspring, the pregnancy has more small bodies to build, and limited birth energy can reduce the number actually born.
• Brood size and parental investment interact directly: many offspring can work for quantity strategies, but each child starts smaller and less provisioned unless pregnancy and offspring investment also rise.
• Juveniles gradually grow into their adult size, force, stamina, soft-body toughness, shell protection, and feeding ability over childhood. Growth uses reserve energy to build new tissue, so underfed juveniles can stall instead of maturing on schedule.
• Predation pressure is often strongest during childhood, because juveniles can fall below the defensive threshold that protects the same species as adults.

Every creature carries 58 genes organised into categories. Genes do not directly control what a creature does — instead, they work together to produce a phenotype: the set of derived physical and behavioural characteristics that determine how the creature moves, eats, sees, thinks, and reproduces.

For example, a creature's energy reserve capacity is not set by a single gene — it emerges from fat, muscle, and organ tissue areas. Movement cost depends on mass, support, usable muscle, muscle profile, appendages, body shape, and terrain. Lifespan is influenced by maturity age, body size, durable active tissue, reserve tissue, and metabolic pace.

Genes are grouped into categories: Sex, Body Core (size, muscle mass, structural tissue, organ tissue, fat stores, general muscle, fast-twitch muscle, endurance muscle), Body Shape (streamlining), Appendages (tail, appendage growth, placement, spacing, length, and fin-or-leg shape), Armour (shell), Intelligence (brain capacity, memory, and cognitive specialisation), Behaviour (fear, mate urgency, exploration, risk tolerance), Movement (preferred speed), Vision (long-range and close-range sight), Diet (plant/meat digestion efficiency, mouth size, mouth type, jaw strength), Colour, and Breeding (maturation tempo, pregnancy, brood-size investment, parental investment, mate signaling).

• Size: Determines visual scale and body footprint. It affects body mass, energy reserves, baseline energy use, movement strength, and many other derived traits.
• Muscle Mass: Active tissue for strength and movement. More muscle increases push power, bite strength, stamina capacity, and energy demand.
• Structural Tissue: Reinforced body frame. More structure improves support and toughness, but adds dense mass that does not push by itself.
• Organ Tissue: Extra internal systems beyond basic life support and digestion. More organs support stamina recovery, pregnancy, and repair, but add living mass and upkeep.
• Fat Stores: Reserve tissue for lean periods. More fat increases energy storage with low upkeep, but it adds mass and does not directly help push, bite, or support the body.
• General Muscle: Balanced muscle profile. Muscle Mass sets total tissue amount; profile genes decide how that tissue behaves.
• Fast-Twitch Muscle: Burst-oriented muscle profile. It gives the strongest short push, but each push spends more stamina and upkeep is a little higher.
• Endurance Muscle: Repetition-oriented muscle profile. It improves recovery and stamina efficiency, but gives less peak push.
• Streamlining: Elongates the body shape. It helps swimmers slip through water more easily, but bulky bodies and visible limbs can still make swimming harder, and it sacrifices tight turning, especially for land manoeuvring.
• Tail Length: Provides water propulsion and can help early land slithering, especially when tail size and body support are strong. Long tails still increase turning burden and can get in the way for mature walkers.
• Appendages: A bud signal, field center/span, spacing, front/rear length, and front/rear surface shape generate paired appendages along the body. Narrow, well-supported appendages become better legs for land; broad fins, flippers, or paddles help water control and can help weak shore crawling before they become leg-like. Long appendages add reach but need support and space, while crowded or poorly balanced fields lose effectiveness.
• Shell Width: Sets potential armour band width around the soft body. Stronger shells express more of that width as physical bulk and load, especially on larger creatures.
• Shell Strength: Makes the shell harder to crack and increases shell material density. Strong shells can fully block weak jaws, but they still add load and powerful adult predators can wear them down.
• Far Vision Distance and Angle: Vision range and width. A narrow field of view sees much further; a wide field of view covers more area but at shorter range.
• Mouth Size: How wide and far the mouth can reach. Bigger mouths make contact easier and help handle larger bites or prey, but plant, carcass, and live-prey value still depends on having the right mouth type.
• Mouth Type: Shifts the mouth from plant-cropping feeder to carrion-tearing scavenger to live-prey-gripping predator. Medium jaws can add scavenging help, but predator-leaning mouth types reduce that carrion bonus again.
• Jaw Strength: Bite force and visible jaw heft for cracking shells, increasing live-prey bite damage, shortening bite handling, and supporting carcass ripping. Strong jaws can push large mouths forward and add a little physical load.
• Plant/Meat Digestion Efficiency: Determines food payoff. Plant digestion improves plant energy gain; meat digestion turns animal tissue into usable energy. Mixed diets need more digestive organ space and upkeep. Live predators still need attack traits such as bite damage, jaw strength, mouth shape, and prey-size handling.
• Body Colour: Determines how well the creature's pigments match plant food. Matching required food colours increases plant energy; missing required colour channels gives none, and extra off-colour pigment dilutes the payoff.
• Brain Capacity: Requests room for advanced hidden processing. More requested units can allow more complex decisions, but they need brain tissue; limited brain-space fit can reduce how many advanced units are expressed.
• Foraging, Threat, Social, and Memory Cognition: These four genes do not add raw brain size. Instead, they bias how advanced brain capacity is spent, so two equally large brains can specialise in different kinds of processing.
• Memory Capacity and Retention: How many useful food opportunities, mate locations, and predator locations the creature requests to remember, and how long those memories last. The first short memory is primitive; additional memory is advanced capacity that can be reduced when brain-space fit is limited.
• Fear Sensitivity, Mate Urgency, Exploration Bias, Risk Tolerance: Personality traits that shape how the brain weighs different drives — flee vs forage, explore vs rest, caution vs boldness.
• Maturation Tempo: Shifts development faster or slower relative to what the creature's body size and structural investment would otherwise require. Faster tempo favors earlier reproduction; slower tempo usually trades into both later maturity and a longer lifespan.
• Pregnancy Duration: Delays birth, spreads prenatal costs over time, and lets embryos develop further before birth, with larger broods starting smaller.
• Pregnancy Energy Investment: Extra prenatal body-building budget a female tries to pay across pregnancy, supporting more of the planned brood, more developed newborns, or extra starting reserve when enough energy is available.
• Brood Size Investment: Genetic investment in larger broods. The 1-100 score maps linearly to a 1-30 planned brood target, but larger broods split maternal carrying capacity into smaller newborns and limited birth energy can reduce actual births.
• Female/Male Investment Time In Offspring: Sex-specific care time represents protection, guarding, feeding, or support before offspring are fully independent. In the simulation it extends that parent's reproductive cooldown and gives juveniles temporary protection after birth. For females, that cooldown starts after birth; for males, it starts at mating.
• Female/Male Investment Energy In Offspring: Sex-specific provisioning represents resources directed into offspring. Female energy investment is paid gradually through pregnancy as extra reserve, yolk, or early feeding support; male offspring energy is reserved at mating and becomes extra reserve for the babies that are born.
• Male Investment Time In Mate: Represents a male protecting or helping provision a mate around reproduction, costing male mating cooldown.
• Male Investment Energy In Mate: Represents an immediate provisioning gift from the male to the female at mating, helping her survive pregnancy and sustain gestation costs.
• Mate Signal Frequency and Volume: How often the creature broadcasts mate-discovery signals and how far they travel. Louder, wider calls are easier to hear but cost more energy per broadcast; an established match can persist after the sound fades.

Creature Anatomy — How Visible Genes Change the Render

Every visual feature of a creature is gene-driven. These cards show the genes that visibly change the static render, with multiple examples for each so you can see the range from low to high or category to category. Other genes still matter, but they change behaviour, metabolism, memory, breeding, or derived stats rather than the sprite itself.

Body Colour (RGB)The red, green, and blue colour genes combine into the body fill. Matching food colour improves energy gain.

Red

Green

Grey

SizeSize changes the creature's overall scale. Larger bodies can carry more tissue and reserves, but need more food, support, and effort to move well.

Small

Mid

Large

StreamliningStreamlining stretches the body into a longer, thinner swimmer. High values help the creature slip through water, though bulky bodies and visible limbs can still make swimming harder, and they hurt tight turning.

None

Mid

Full

Muscle MassMuscle mass builds active tissue. More muscle gives stronger pushes and bites and a larger short-term stamina reserve, but raises body mass and food demand.

Low

Mid

High

Fat StoresFat stores add reserve tissue for lean periods. More fat increases the hunger buffer with low upkeep, but adds weight without helping push, bite, or support the body.

Low

Mid

High

Organ TissueOrgan tissue represents extra internal systems beyond basic life support and digestion. More organs help recovery, pregnancy, and repair, but take body space and cost energy to maintain.

Low

Mid

High

Body Composition and DensityBody composition shows what the soft body is made from: structure, muscle, fat, organs, brain tissue, and body fluid. Structure supports and toughens the body, muscle powers movement and bites, fat stores energy, organs support digestion and recovery, brain tissue pays for cognition, and body fluid is basic living mass. When appendages are visible, structure and muscle also make their bases sturdier.

Strong Lean

Balanced

Underbuilt

Tail LengthTail length changes the rear body and tail shape. Longer tails can power swimming and help early shore slithering, but large tails make tight turns harder and can get in the way of mature walking.

None

Short

Long

Appendage Bud SignalAppendage bud signal controls how strongly the body grows paired side appendages. Weak signals leave tiny or missing buds, while strong signals fill the available region with fins, paddles, or legs.

None

Weak

Strong

Appendage FieldAppendage field center and span decide where paired appendages appear along the body. Forward fields favor steering and braking, rear fields favor push and stability, and broad fields can support multiple pairs.

Front

Rear

Long Field

Appendage SpacingAppendage spacing controls how closely repeated pairs can form. Tight spacing favors many small contacts, while wide spacing favors fewer appendages with more room.

Tight

Mid

Wide

Appendage LengthFront and rear appendage lengths set reach at each end of the field. Short front appendages can act as fins or braces, while longer rear appendages can help crawling, pushing, and later walking.

Even Short

Front Long

Rear Long

Appendage SurfaceFront and rear appendage surface values shape each end of the field from narrow leg-like limbs toward broad fins, flippers, or paddles. Broad appendages help water control and weak shore crawling, while narrow supported appendages make better walking legs.

All Legs

Front Fins

All Fins

Shell WidthShell width sets potential outline thickness around the body. Shell strength controls how much of that width becomes visible physical armour and load.

None

Mid

Thick

Shell StrengthShell strength darkens the shell outline. Stronger shells have denser shell material and are harder for weak jaws to crack, though powerful predators can still wear them down.

Weak

Mid

Strong

Mouth SizeMouth size changes visible gape and feeding reach at the front of the body. Big mouths can hang farther forward when paired with strong jaws; feeding value still depends on mouth type.

Small

Mid

Large

Jaw StrengthJaw strength shows as heavier mouth structure, and meat-adapted mouths also show stronger tooth cues. Strong jaws can push large mouths forward, make live bites more forceful, help crack shells, and support ripping carcasses, but they add a little physical load.

Weak

Mid

Strong

Mouth TypeMouth type controls the broad mouth shape: herbivores keep a soft rounded mouth, scavengers develop a heavier carrion mouth, and predators show split jaws with teeth. Mouth size and jaw strength control how large and forward that shape appears.

Herbivore

Scavenger

Predator

EyesEye size grows with overall vision capacity. Creatures with broader or longer sight display larger eyes in the render.

Small

Mid

Large

Far Vision DistanceLonger vision distance pushes the normal forward cone outward. Preferential close-awareness range has its own gene and is capped more tightly as it becomes wider.Gold shows normal forward sight; blue shows preferential close-range sight. In the simulator, FOV cones can be toggled on and off from the command bar.

Short

Mid

Far

Far Vision AngleNarrow forward vision reaches farther; wider vision covers more area at shorter range. Panoramic preferential vision stays close-range rather than becoming long-distance awareness.Gold shows normal forward sight; blue shows preferential close-range sight. In the simulator, the command bar lets you toggle FOV cones on and off.

Narrow

Mid

Wide

SexSex is mostly internal, but males show a small line below the body while females do not.

Female

Male

Male Investment In MateFor males, the line below the body gets longer as mate investment increases. It reflects immediate energy gifts to the mate and time spent protecting or provisioning her through pregnancy.

Low

Mid

High

The genetics system models real diploid inheritance. Each creature has pairs of chromosomes — one from each parent. Genes sit on these chromosomes and are inherited through gamete formation with crossover and mutation.

Sex is determined by sex chromosomes: XX = female, XY = male. By default, the Y chromosome carries only the sryGene for sex determination, while Autosome 1 carries the other genes. You can customise which genes sit on which chromosomes using the Karyotype Templates editor.

When a creature reproduces, it forms gametes (egg or sperm) by selecting one chromosome from each pair. During this process, crossover occurs: homologous chromosomes swap segments at random points, creating new gene combinations. This is a key source of genetic variation — even without mutation, crossover shuffles existing alleles into novel combinations.

Mutation adds further variation. Each allele has a chance of mutating during gamete formation. Mutations are small random changes — some genes like colour mutate in larger steps, while precision traits like digestion efficiency mutate in smaller steps. Values are always kept within each gene's valid range.

• Gene expression depends on each locus's expression mode. Additive loci average finite maternal and paternal allele values. Dominant/recessive loci express the allele with the highest dominance rank; same-rank pairs average, so a lower numeric value can dominate when its rank is higher.
• XY males express X-linked and Y-linked genes hemizygously (single allele, no averaging) because X and Y carry different genes.
• Crossover produces a random number of swap points along each chromosome, mixing segments from both parents into new combinations.
• XX females cross over between their two X chromosomes. XY males do not — they pass an intact X or Y at random.
• The expressed genotype is then converted into a calculated phenotype — the derived traits like push strength, stride length, turning ability, baseline energy use, and lifespan that emerge from genes working together.

Speciation occurs automatically when an offspring's actual allele pairs no longer fit the allele summaries of the species candidates it is allowed to join. The simulation uses a weighted genetic distance metric over chromosome structure, known allele variants, and expressed values to detect this.

Genetic distance treats known allele variants as very close matches. Hidden unknown recessive alleles can stay within the parent species when the expressed value still fits, while visible dominant/recessive homozygotes or large expressed-value shifts contribute more distance. New, duplicated, or moved loci still count as structural change.

Not all genes count equally — functional traits like diet, size, muscle mass, fat stores, streamlining, and shell contribute much more to speciation than cosmetic traits like colour. This means a creature can change colour significantly without speciating, but a shift in diet or body plan triggers a new species more readily.

When an offspring no longer fits the relevant parent-lineage species candidates, it is assigned to a new species. For ordinary same-species parents, the checked lineage is the shared parent species and its direct child variants. New species are named hierarchically: if the parent species is 'Alpha', the first branch becomes 'Alpha.1', the next 'Alpha.2', and sub-branches become 'Alpha.1.1', etc. This creates a species tree you can visualise in Data Analysis.

Freshly branched child species first appear in the in-game 'Emerging Species' section once both sexes are represented. They become established only after building an adult breeding population — at least 10 adult members, including at least 5 adult males and 5 adult females — then move into the main Species list and count as established species in the HUD.

Once a new species forms, sibling lineages begin to diverge. Creatures can breed within their own species and with recorded parent species, but not freely across every sibling branch; sibling gene flow stays limited unless a creature's parentage explicitly includes that species.

• Speciation is not a single dramatic event — it emerges gradually as mutations accumulate and selection pushes a subpopulation away from the original species profile.
• Hybrid offspring (parents from different species) first try to join a matching species from either parent lineage: the two parent species or their direct child variants.
• If no parent-lineage candidate fits, a hybrid can create a new hybrid-derived species. Its species-tree parent is the actual parent species that is genetically closest to the child.
• Hybrid-derived creatures remain compatible with their own species, recorded mother and father species, and other hybrids that share one recorded parent species. This allows limited backcrossing and hybrid-zone gene flow while still keeping unrelated sibling branches separated.
• You can watch speciation unfold in the Species Tree view, which shows branching lineages and extinct branches.

Every creature has a small neural network brain that processes sensory inputs, internal state, and memory to decide what to do. There are no hard-coded rules — all behaviour emerges from the brain's inherited and evolved connection weights.

The brain reads a wide range of inputs — hunger, stamina, what it can see, what it remembers, what's nearby, and its own body capabilities — then produces outputs that drive behaviour and movement. The brainCapacity gene controls how many processing units can be expressed. More units allow more nuanced decision-making but cost more energy to maintain.

The four behaviour drives are Forage (seek food), Flee (escape predators), Mate (find a partner), and Wander (explore). The drive with the highest score wins, setting the creature's current action. A separate Rest drive can suppress movement — when rest is strongest, the creature keeps its current action but does not push, allowing stamina to recover. Two additional outputs control turning (left/right) and one controls thrust intensity, with actuator deadbands and turn-budget limits applied after the network fires. A final output triggers mate signaling. Scavengers and hunters can receive extra information about carcasses, prey vulnerability, and their own damaged defences.

• Body-state signals: hunger level, energy surplus, maturity, mating readiness, pregnancy status, sex, stamina, recent exertion, and whether the creature is tiring or recovering.
• Body awareness inputs: on-land status, land/water capability, body size, movement cost, turning agility, diet efficiencies, brain metabolic cost.
• Movement inputs: coasting value, sustainable push level, recent distance moved, speed relative to preferred range, barriers ahead/left/right.
• Sensory inputs: the best-valued usable plant food or carcass, plus nearby prey for live hunters, mates, and predators — each represented with proximity and angle signals.
• Food-web inputs: carcass freshness and competition, prey defence and vulnerability, and the creature's own shell damage can all shape decisions.
• Memory inputs: remembered food opportunities, mates, and predators with confidence scores and positions.
• Social inputs: neighbour count, same-species ratio, other-species ratio, opposite-sex ratio, and visible pregnancy ratio.
• Personality genes (fear sensitivity, mate urgency, exploration bias, risk tolerance) scale specific inputs and outputs, giving each creature a temperament.
• Cognition-specialisation genes decide which advanced processors come online first as brain capacity grows. This lets one lineage evolve into strong foragers while another of similar brain size becomes better at threat detection, social behaviour, or memory.

Brain View — Reading a Creature's Decisions

The selected-creature panel includes this live network view. Sensory and body-state signals are on the left, hidden brain processors are in the middle, and behaviour outputs are on the right. Cyan links and nodes indicate signals pushing behaviour forward; orange signals are suppressing or counteracting them. In this example, hunger keeps food interest decisive, while surplus energy and a matched mate suppress some food steering and push mate-directed turning.

Brains are inherited and mutated alongside body genes. A child's brain is bred from both parents' neural networks, creating heritable behaviour that evolves over generations.

During reproduction, each connection weight in the child's brain is randomly copied from one parent or the other. Small mutations are then applied — most are subtle tweaks, but occasionally a larger change occurs. The number of active processing units can also shift slightly between generations, allowing brain complexity to evolve up or down.

New species start with a hand-crafted seed brain that provides baseline survival behaviours — basic predator avoidance, food seeking, mate approach, and wandering. Evolution quickly modifies this starting point. Over many generations, brains can develop specialised strategies: efficient foraging patterns, effective predator evasion, optimal pacing between rest and movement, or aggressive mate-seeking behaviour.

• More requested hidden neurons can allow more complex decision-making, but they require brain tissue. Expressed brain tissue sets metabolic cost, and limited brain-space fit can reduce active advanced units.
• Brain behaviour is not pre-programmed per species. Two creatures of the same species may behave differently based on inherited brain weights.
• The hidden layer has 20 named conceptual neurons split into two tiers: 10 primitive and 10 advanced.
• Primitive neurons are always active regardless of brain capacity. They provide the core behaviours every creature needs: food interest, thrust control, wandering, steering toward food, mate interest, steering toward mates, and world-edge avoidance.
• Advanced neurons are grouped into foraging, threat, social, and memory specialisations. Brain capacity and inherited brain structure set the nominal advanced units, while the four cognition genes bias which groups activate first and physical brain fit decides how many actually express.
• This means two creatures can both evolve larger brains without becoming smart in exactly the same way. One lineage might prioritise food-value evaluation and foraging, while another emphasises threat assessment, mate-signaling strategy, or memory.
• A creature with minimal brain capacity can forage, wander, seek mates, steer toward food and mates, and avoid barriers. Memory still requires memory capacity, while predator handling and more nuanced risk decisions require advanced brain units.
• Because brains and body genes co-evolve, a lineage that evolves better vision may simultaneously evolve brain wiring that better exploits that vision.

At any moment, each creature is in one of four behavioural states. The state is determined by the brain's strongest output drive. A separate rest drive can suppress pushing without becoming its own visible action state.

Creatures can remember food opportunities, mates, and predators they have seen. Memory capacity and retention are gene-controlled traits, but their expressed values can be reduced when requested brain tissue does not physically fit.

Each memory slot stores a type (food, mate, or predator), a position, and a priority score based on importance, recency, and how many times the item was seen. Food memory can point to plant food, carcasses, or edible live prey depending on what the creature can use. Predator memories are prioritised highest, followed by mates and then food. Memories decay over time and are eventually forgotten.

Memory feeds directly into the brain as inputs: remembered food/mate/predator positions and confidence values. A creature with high memory capacity and retention can navigate back to productive food opportunities, recall where mates were last seen, and remember dangerous areas — all conferring survival advantages.

• Memory capacity: How many things the creature can remember at once. The first short memory is primitive; additional memory is requested by the memoryCapacity gene and can be reduced if brain-space fit is limited.
• Memory retention: How long memories last before fading. Requested by the memoryRetention gene, then shortened if brain-space fit is limited.
• Memory has a metabolic cost through brain tissue demand, creating a trade-off between awareness, body space, and efficiency.
• Carcasses and hunt remains can be remembered as food opportunities, but they are short-lived: stale, eaten, or removed remains quickly become useless and are purged from memory.
• Dead or removed remembered items are automatically purged from memory.

Each simulation run produces different outcomes, but certain evolutionary patterns tend to emerge depending on the environment.

In the early generations, the population typically crashes as poorly adapted creatures starve or fail to reproduce. Survivors carry the genes and brain wiring that happened to work in the initial environment. Over time, you can expect to see several common evolutionary trajectories:

• Movement efficiency: Creatures evolve toward bodies that waste less energy. Streamlined tails suit swimmers, leg balance and body support shape walkers, longer supported legs can create longer strides, and muscle profile helps lineages pace effort and recovery. Early land lineages can survive through tail-assisted slithering before becoming stronger crawlers or walkers.
• Food colour specialisation: If one food colour dominates, creature body colour tends to drift toward that colour over generations, because colour-matched creatures extract more energy per food item. Changing food ratios mid-simulation can cause rapid adaptation or mass extinction.
• Habitat and movement specialisation: Habitat labels describe aquatic, semi-aquatic, amphibious, and land-specialist niches. Land movement labels describe the dominant gait from slithering and crawling through transitional walking, hopping, walking, and running. Water movement badges stay focused on strong swim speed; detailed tail, fin, braking, and glide scores live in the phenotype panel.
• Predator-prey arms race: As predators evolve, prey species face pressure to develop defences — larger bodies, heavier or tougher body plans, harder shells, higher fear sensitivity, faster flee responses, and better predator memory. Predators in turn may evolve stronger jaws, bigger mouths, better pursuit, sharper vision, and lower risk tolerance.
• Scavenging niches: Carcasses can reward early meat-digestion mutations before a lineage is strong enough to hunt live prey. These lineages may evolve toward better scavenging, foraging cognition, and moderate jaws rather than all-in hunting.
• Shell evolution: When predation pressure is high, shell width and shell strength tend to increase, making creatures harder to bite. Strong wide armour adds bulk and load, reduces agility, and damaged shells require repair after attacks.
• Brain sophistication: Brain capacity may increase over time as smarter creatures make better foraging and predator-avoidance decisions. But brain neurons cost metabolic energy, so overly complex brains are penalised in lean environments.
• Reproductive strategy divergence: Some lineages evolve high parental investment (fewer, more developed or better-supported offspring), while others evolve low investment (many fragile offspring). Environmental stability tends to favour investment; chaotic environments favour quantity.
• Food scarcity adaptations: When food is scarce, evolution favours energy-efficient movement, lower energy needs, smaller body sizes, better endurance recovery, and wider foraging vision over raw speed.
• Speciation events: As subpopulations adapt to different niches (land vs water, different food colours, different predation strategies), genetic distance accumulates until new species branch off. The Species Tree visualises this branching.

The Spawn Creature panel lets you either create a brand-new species template or add more creatures from an existing species already in your library.

• Click Spawn Creature in the controls bar. The side panel opens with chromosome-aware gene editors that can be viewed as the individual Creature genotype or by Chromosomes.
• To create a new species, click Create New Species and set starting chromosome, gene, and allele values using sliders or number inputs. Each gene shows its valid range and a description of what it affects.
• Genes are organised into categories such as Body Core, Body Shape, Appendages, Armour, Intelligence, Behaviour, Movement, Vision, Diet, Colour, and Breeding. You can also switch to the Chromosomes view to place genes on X, Y, or autosomes and choose inheritance modes.
• When you save a new species, those founder chromosomes create the fixed library-template allele summary. When that species is spawned into a simulation, the run allele pool can grow as compatible descendants add observed variants; the saved library template remains the founder-derived starting point.
• To experiment with an existing saved species, select it and enter God Mode. This unlocks a temporary spawn-only chromosome/gene draft so you can introduce a specific trait into the population, add an unusual allele combination to the gene pool, and then watch to see whether that change spreads, survives only in a niche, or dies out.
• Exit God Mode discards the temporary draft and returns to the saved founder chromosomes. Reset to Default restores the saved founder chromosomes while staying in God Mode so you can keep experimenting.
• Use Spawn Female or Spawn Male in the Creature tab to spawn the selected allele-copy combination. Use Add Female or Add Male in the population controls to sample carried copies from the selected species allele pool for one creature.
• You can add multiple species in the same simulation to create competition, predator–prey dynamics, or niche separation.

Simulation Settings let you choose manual or automatic food production for land and water, set food ceilings and colour ratios, tune carcass decay, and adjust mutation pressure for future births.

• Open Simulation Settings from the controls bar.
• The panel is split into Environment, Genetics, and Performance sections. Genetics appears under a Mutations subheading.
• For each terrain (land and water), you can choose Manual or Auto food production, adjust the manual food rate and max, and change colour distribution. You can also change how long carcasses last before decaying. This lets you make one habitat abundant and another harsh, or tune how much scavenging matters.
• Food Rate controls how many plant-food items appear per simulated minute in Manual mode. Auto calculates the rate from area, balanced creature load, expected food value, and colour ratios, then reduces it while the terrain is crowded.
• Auto Land Food watches the most crowded populated landmass. If an island grows crowded, land food cools down from the area-calibrated rate and then recovers gradually as crowding clears.
• Auto Water Food watches global water crowding. It cools down from the area-calibrated rate when swimmers crowd the water and recovers gradually when crowding clears.
• Max Food controls the manual-mode ceiling. Auto Food uses land or water area for its effective runtime cap, so large habitats can fill enough food and small edited habitats stop sooner.
• Colour Ratios change which body colours are rewarded. If red food becomes dominant, creatures that drift toward red body colour gain more energy and are more likely to survive and reproduce.
• Carcass Decay Time controls how long carcasses and hunt remains stay useful after they appear. Longer decay creates more scavenging food and can support carrion-eating lineages; shorter decay makes remains a brief opportunity and keeps plant food more central.
• Genetics exposes Mutation Chance and Mutation Size Multiplier. These affect body genes only, not brain mutation. Mutation Chance controls how often inherited body genes mutate during reproduction. Raising it means each offspring is more likely to carry one or more new genetic changes, which increases variation and can speed adaptation, but also raises the number of harmful mutations. Mutation Size Multiplier controls how large those body-gene mutations tend to be when they happen. Higher values create bigger jumps away from the parents' traits, which can accelerate evolutionary change and sometimes speciation, but they also make poorly adapted offspring more likely. These affect future births only, so they change the pace and volatility of evolution rather than modifying creatures already alive.
• All changes stay local until you click Apply at the bottom of the panel. Cancel restores the last applied settings.
• Each section also has a Reset to Defaults button. That only resets the local draft for that section until you click Apply.
• Reducing Food Rate or maximum count creates scarcity in Manual mode. This tends to favour energy-efficient creatures, strong foragers, and species that can survive lean periods.
• Changing colour ratios shifts which body colours are advantageous. A sudden shift toward red food will pressure creatures to evolve red body colour over generations.
• Setting land or water Food Rate to zero can force scarcity on that terrain in Manual mode. Switching that terrain back to Auto returns food production to the habitat-calculated flow and then applies crowding cooldown.
• Extreme settings can cause extinction events — intentional or accidental. These can be interesting evolutionary experiments.

The toolbar provides controls for managing the simulation's speed, camera, and visual display.

• Start / Restart: Opens the habitat picker so you can choose the starting world before launching a fresh simulation.
• Saved Simulations: Opens the saved-simulation panel so you can load a previous run, replace one with a new simulation, or delete one to free a slot.
• Pause / Resume: Freezes all simulation logic. The simulation also auto-pauses when you switch browser tabs.
• Speed Toggle: Choose Auto Speed or a manual speed from 1× to 10×. Auto Speed raises the sim toward the fastest smooth speed the browser can sustain, steps down under sustained frame pressure, and only widens AI decision cadence as a fallback once it is already at 1×. Manual speeds can still step down if the browser cannot sustain the chosen speed, but they do not climb back up automatically.
• Zoom +/−: Adjusts the camera zoom from 0.25× to 2.0×. You can also zoom with Ctrl/Cmd + scroll wheel.
• Toggle FOV (Field of View): Shows or hides the vision cones for all creatures. Useful for understanding what each creature can see, but performance-heavy with large populations.
• Toggle Action Dots: Shows or hides the current-action dot on each creature. The dot is colour-coded by behaviour: red = flee, orange = forage, green = mate, yellow = wander, blue = rest, purple = pregnant.
• Click a creature: Opens the Selected Creature Panel showing full inspection data — all genes (maternal, paternal, expressed), current drives, brain stats, memory, children, family species, reproduction state, compatible mate controls, calculated phenotype values, and more.

The simulator keeps local rolling saves so you can come back later and continue a run with its world state, creatures, and analysis history intact.

• Up to 3 saved simulations are kept locally in your browser at once.
• Each simulation uses a single rolling autosave slot. As that run continues, new autosaves overwrite that run's previous autosave rather than creating extra save files.
• Autosaves happen every 2 minutes of real time, and also when the simulation is paused manually, when the tab is hidden, when the page is being left, and before loading or restarting into another run.
• Loading a saved simulation restores its creatures, food, islands, species history, graphs, and runtime settings, then opens it in a paused state so you can inspect it before continuing.
• Starting a brand-new simulation uses a save slot. If all 3 slots are already occupied, Saved Simulations can replace an existing run with a new one or you can delete a run first.
• Saved simulations live only on this device and in this browser. They are not synced to a server or account.

The Data Analysis modal provides several views for tracking evolutionary trends and population dynamics.

• Population Graph: Shows population count over time, broken down by species. It also compares births to creatures reaching adulthood, making survival through childhood visible.
• Gene Distribution Graph: Displays the spread of any gene's values across the current population. See whether a gene is converging (strong selection) or broadly distributed (weak selection).
• Gene Correlation Heatmap: Shows correlations between pairs of genes across the population. Reveals linked traits — e.g., do larger creatures also tend to carry more structural tissue, muscle, or fat?
• Species Gene Profile Graph: Compares average gene values across different species. Useful for seeing how species have diverged.
• Mutation Analysis: Summarises which genes are mutating most often, in which direction, and by how much. Useful for spotting where variation is entering the population and whether change is balanced or biased.
• Species Tree: A phylogenetic tree showing how species have branched over time. Extinct branches are visible, telling the story of failed lineages.
• Selected Creature Panel: Click any creature to inspect its full genetic profile, brain state, current drives, children, parentage, species origin, current compatible mates, and all calculated phenotype values. You can also view the creature's thought process in real time through the live brain visualisation.
• Population snapshots are recorded every three minutes of game time, building up a historical record for graph visualisation, including births, deaths, and adulthood counts.

The Karyotype Templates editor lets you control the chromosome structure — which genes sit on which chromosomes and how they are linked during inheritance.

Karyotype templates are optional shortcuts: you can use one to start a species layout, or ignore them and edit chromosomes directly in the species builder.

By default, the Y chromosome carries only the sryGene for sex determination, while a single autosome carries all other genes. X-linked genes can be inherited by both sexes, while Y-linked genes pass only through males. This means moving a gene onto the X or Y chromosome changes not just linkage, but which sex can inherit and express it. You can redistribute genes across multiple autosomes to change linkage groups. Genes on the same chromosome tend to be inherited together (unless crossover separates them), while genes on different chromosomes assort independently.

Changing the karyotype affects the rate at which gene combinations are broken up or preserved across generations. More chromosomes means more independent assortment; fewer means tighter linkage. This is a powerful tool for advanced experiments in inheritance dynamics.

The easiest way to enjoy the simulator is to treat each run like an evolutionary experiment. Here is a suggested first session:

• 1. Click Start Simulation, choose a starting habitat, and launch the world.
• 2. Click Spawn Creature to create your first species. Try the starter chromosome/gene values or adjust a few — body size, colour, and diet efficiency are good starting points.
• 3. Watch the founding population for a minute. Are they finding food? Are they surviving?
• 4. Open Simulation Settings and experiment: try Manual food rates to see how scarcity changes behaviour, or shift food colours to pressure colour adaptation. Auto Food is useful for long runs where you want uncrowded habitats to stay well supplied while crowded habitats cool down.
• 5. Add a second species with different genes to compare. Make one a water specialist (high tail, few narrow appendages, streamlined) and another a land specialist (rear-weighted leg-like appendages for push, front control appendages, low streamlining).
• 6. Open Data Analysis to watch population graphs, gene distributions, and the species tree.
• 7. Toggle FOV visibility to see what creatures are perceiving. Toggle Action Dots to read behaviour at a glance.
• 8. Click individual creatures to inspect their genes, brain drives, memory, and family tree.
• 9. Speed up the simulation (2×) for longer experiments and watch speciation events emerge in the species tree.
• 10. Evolution takes time. Let the simulation run, then come back 30 minutes later to see how the population, species tree, and gene distributions have changed.
• 11. Try creating a predator or scavenger species. Moderate meat digestion can make carcass feeding useful, but live hunting needs attack anatomy too: predator-shaped mouths, larger gape, strong jaws, enough bite damage, and prey size handling. Moderate mouths suit scavenging, while larger mouths and stronger jaws help with live prey.
• 12. Keep in mind that the simulation stops running when your screen locks. If you want to leave it running for a while, increase your computer or mobile device's screen-lock delay first.

Key terms used in the simulation.

• Allele: A specific value and identity for a gene at one locus. Symbols such as A, B, a, or b name variants within a species locus; each diploid creature carries at most two copies at that locus.
• Autosome: A non-sex chromosome. Carries most body, behaviour, and survival genes.
• Body Composition: The selected creature panel's split of total area into shell plus soft-body tissues: structural, muscle, fat, organ, brain, and body fluid.
• Calculated Phenotype: The set of derived traits (push strength, stride length, baseline energy use, lifespan, energy reserve capacity, etc.) that emerge from genes working together. No single gene controls these — they are produced by combinations of multiple genes.
• Carcass: A temporary meat resource left by some deaths. Full carcasses can come from starvation, old age, or manual removal, while predation can leave smaller hunt remains. These resources fade, lose available meat as they decay, shrink as creatures extract energy, and can be scavenged by creatures with usable meat digestion and a carrion-capable mouth.
• Compatible Mate: A living opposite-sex creature that both sides can currently consider for reproduction. Compatibility includes adulthood, mating readiness, pregnancy state, and species lineage, including hybrid lineages with a shared recorded parent species.
• Crossover: The exchange of gene segments between homologous chromosomes during gamete formation. Creates new combinations of existing alleles.
• Diploid: Having two copies of each chromosome — one from each parent. All creatures in this simulation are diploid.
• Dominant/Recessive: An inheritance mode where dominanceRank decides expression. Rank 1 beats rank 0 even if its numeric gene value is lower; same-rank pairs average.
• Additive Inheritance: An inheritance mode where finite maternal and paternal allele values are averaged to produce the expressed value.
• Expressed Gene: The final gene value after combining maternal and paternal alleles via the inheritance rule.
• Founder Chromosomes: The chromosome-aware baseline saved with a species template. It stores X, Y, autosomes, per-locus values, expression modes, and whether the species' Y baseline has been observed.
• Creature View: The spawn-panel view for choosing an individual creature's carried allele copies and previewing allele-aware expressed gene values before phenotype tradeoffs. Species identity and variation are tracked with the run allele pool.
• FOV (Field of View): The angular width and distance of a creature's vision cone. Controls what the creature can see.
• Gamete: A haploid cell (one chromosome from each pair) produced during reproduction. Egg or sperm equivalent.
• Genetic Distance: A weighted measure of how far a creature's allele pairs, locus structure, and expressed values have drifted from a candidate species allele summary. Used to decide whether the offspring fits that species or needs a new branch.
• Genotype: The creature's full set of chromosome pairs carrying all alleles.
• Hemizygous: A gene present on only one chromosome (e.g., X-linked genes in XY males). Expressed directly without averaging.
• Homologous Pair: Two copies of the same chromosome, one from each parent.
• Hybrid Parentage: A creature whose recorded mother and father belong to different species. It may still belong to one parent-lineage species, or become a new hybrid-derived species if no parent-lineage species fits.
• Hunger: The creature's energy store. Depletes via metabolism and movement. Refilled by eating. Zero = starvation death.
• Jaw Strength: Bite force and visible jaw heft used for cracking shell defences, ripping carcasses, making live-prey bites more dangerous, shortening chew time, and adding tooth cues on meat-adapted mouths. Strong jaws add a little physical load.
• Karyotype: The chromosome structure defining how genes are organised and linked.
• Karyotype Template: A reusable chromosome-layout preset. Choosing one copies its layout into a species; species are not linked back to templates after creation.
• Matched Mate: A chosen reproductive target created from recent mate signaling. The match can continue after the original call fades, but it ends if either creature becomes unavailable, pregnant, incompatible, inactive, or not ready to breed.
• Mate Signal: A short-lived broadcast used for mate discovery. Signal volume and body size set how far it travels, frequency sets how often calls are made, and each call costs energy.
• Muscle Mass: Active tissue investment. More expressed muscle increases movement power and stamina capacity, but also raises upkeep and body load.
• Muscle Profile: The general, fast-twitch, and endurance muscle genes split existing muscle tissue between balanced power, burst force, and cheaper repeated effort.
• Organ Tissue: Adaptive body-system investment above core organs. More adaptive organ tissue supports stamina recovery, while adding living mass and upkeep.
• Relative Metabolic Intensity: How expensive the creature's body plan is to maintain for its size. Active muscle, brain, vision, memory, jaw load, and recovery all contribute.
• Baseline Metabolism: The resting energy cost of staying alive. Bigger reserves and more expensive body plans both raise it.
• Mutation: A random change to an allele value during gamete formation. Mutation preserves the allele's symbol, expression mode, and any dominant/recessive rank.
• Mouth Type: The feeding shape of the mouth, ranging from plant-cropping through carrion-tearing to live-prey-gripping.
• Neuroevolution: The process of evolving neural-network brains through inheritance and mutation across generations.
• Phenotype: The set of expressed gene values after combining alleles — what the creature actually looks and behaves like. Also refers to the derived traits that emerge from genes working together. Species compatibility is tracked by species lineage and recorded parent species rather than by a single phenotype field.
• Selection Pressure: Environmental factors (food scarcity, predation, habitat) that cause some traits to be favoured over others.
• Shell Integrity: Current shell durability. It can be damaged by predator bites and repaired when the creature has enough energy.
• Speciation: The formation of a new species when a creature's allele pairs and expressed values have drifted far enough from the relevant parent-lineage species allele summaries. Hybrid offspring check both parent lineages before creating a new hybrid-derived branch.
• Species Tree: A visual phylogenetic diagram showing how species have branched from common ancestors.
• Stamina: Short-term exertion reserve for burst movement. Muscle tissue sets most of the tank size, organs support it, and muscle profile, hunger, current depletion, and recent exertion shape how quickly it is spent and refilled.
• Structural Tissue: Dense frame tissue that improves load support and toughness, but adds mass without directly creating push.
• Fat Stores: Low-upkeep reserve tissue investment that improves energy reserve capacity and survival through lean periods, while adding mass that must be moved.
• Streamlining: Body elongation that helps swimmers slip through water more easily, though visible appendages and bulky bodies can still slow swimming. It also sacrifices tight turning, especially on land.
• Appendage Field: The body region that can produce paired appendages. Field center, span, spacing, and bud signal decide where appendages appear and how many functional pairs develop.
• Appendage Shape: Length and surface genes shape each appendage from narrow leg-like limbs toward broader fins, flippers, or paddles. Front and rear appendages can evolve different shapes.

Frequently Asked Questions

Technical Notes

• Auto-pause when switching tabs: Browsers throttle or suspend background tabs to save resources. Because of this, the simulation automatically pauses when you switch to a different tab. This is a browser limitation — JavaScript timers, rendering, and physics all slow down or stop in inactive tabs, which would cause the simulation to desync.
• Use a separate window: If you want to browse other content while the simulation runs, open it in a separate browser window (not a tab). A separate window remains active and visible to the browser, so the simulation continues running normally. The Info page already opens in its own window for this reason.