A player's guide to the evolution simulator at genesis.ai-ministries.com (the page itself is titled GENESIS AGAIN). What it is, how to play, how much of it is real science, and what is not in it yet.
1. What GENESIS is
GENESIS is a simulation, not a game: a simulation with a creator-guided god mode. It runs life from a soup of self-copying molecules toward animals, and possibly people, by evolution alone. Every creature carries DNA. Its body, habits and abilities are read from that DNA, and copying errors are the only way anything new appears.
You do not make creatures. You shape the world: the land, the climate dials, the timing of disasters, the odds of each kind of change in the DNA, and who may pair. Nature does the rest.
There is no fixed road. Some worlds stall with microbes or jellies, some reach fish or reptiles, some make kinds that never lived on Earth. Humans are one possible outcome, not the goal.
The whole sim runs in your browser in one page. Nothing is installed.
2. How to play
The screen
Top line: the Earth clock, where your world's life stands on Earth's timeline ("life at ..."), the generation count, when the world was last saved, and at the end the time scale: how many years one tick is in the current era ("1 tick = 2,000 years") and how long this world has run on this computer ("running 3 h 12 min"; a new world starts at 0).
Buttons: Pause / Play, Step (one tick), New world (with a Seed number: the same seed gives the same planet), the Lab picker, and four views: Region, World, Tree of life and Communities.
Show: filters the map: everything, no replicators, no single cells, only single cells, 0-2 steps, 3-5 steps, 5+ steps, 8+ steps, or only the most advanced; the Species tab ticks apply on top. It is only a view: hidden kinds are not drawn but are still alive and listed in the Species tab, and the map says how many of how many are drawn.
Select area: drag a box on the map (or hold Shift and drag) to list everything inside it.
The chart bar ("What life can do"): every step of life, grouped. Green means the step exists and something alive carries it. Brown means it appeared once and is now lost. Tap a step to see what it does, what it needs, what it cannot be combined with, its gene, and when it first appeared. At the end, "Closest to human" shows the living species with the most of the 23 human-route steps.
The map: the lab you are watching, with a minimap in the corner.
Side panel tabs: Now, Labs, Species, Creator, Chronicle, Selected.
The ? button at the bottom right sends a report (see below).
The tour: 14 steps that light up each part of the page in turn (the map, the top line, the views, Show, the steps of life, each tab, the ? and wiki links). It opens once on your first visit; the "tour" link next to "wiki" at the bottom right replays it, and Esc closes it.
Tree of life has its own button in the main header.
Who has it: tap a step on the steps bar. "Show me one (N alive have it)" picks a living creature that has it (a young, well-fed one), follows it and opens it; press again for the next one. Below it, every living species with the step is listed (tap one to open it in the Species tab), and "Mark them on the map" rings every carrier.
Controls
Do this
To get this
Drag the map, or Arrow keys / WASD
Move the view around the lab
Mouse wheel on the region map
Zoom out, up to the whole lab
Click the minimap
Jump to that part of the lab
Click a creature
Select it and follow it; the Selected tab shows its species, line, DNA and what it has learned. If it dies, the camera moves on to a young, well-fed member of the same species nearby (or else the nearest of its kind) and says so; when none are left, following stops and says why
The Punnett square (Selected tab, bottom of the DNA panel)
The selected creature's two copies against its nearest mate's, in a 2 x 2 grid: one step gene (W working, w broken; W is dominant) and the size dial (both copies show). The four squares are the four equally likely children.
"Watch the most advanced" (Selected tab)
The camera stays on the creature furthest along, and moves on when a better one appears
Mouse wheel in the World or Tree view
Zoom the globe, scroll the tree
B or the ? button
Open the report form
Esc
Close the report form or the step panel
The labs (zones)
Each world has 12 labs: places spread across one generated planet, from the tropics to near the poles (up to about 64 degrees of latitude), each part sea and part land. Each lab is four screens large. The first lab is the mildest. The land opens up: a lab's map is a window on the planet. When 20 animals with legs walk its land, and again when grasslands open, the window grows twice as wide and tall (four times at most) and moves inland, so the old ground sits at its seaward side. The new land is the planet's own terrain there; plants, soil and lakes carry over where the old map was, and creatures keep their place. The World view follows the grown window, with a gold box for its size. The World view shows the globe with a pin for each lab; the Labs tab lists them, and tapping one takes you there.
Creatures that leave a lab can arrive in a neighbouring lab or wait in a "wider world" pool and come back later, which lets life return after a disaster.
Which labs run: the Labs tab has a box for each lab. The lab you are watching always runs, ticked labs run too (any number, 1 to 12; more is slower), and the rest wait where they are. The Lab list in the header marks each lab "● watching", "● running" or "○ waiting".
Creator and guided mode
The Creator tab holds everything you can change. Each change is written in the Chronicle.
Evolution: "Nature runs free" (the default) leaves every copying error to chance. "Guided" gives each of 12 groups of steps a weight from 0 to 5. Above 1, a miscopy in that group's genes lands on the working base more often; below 1, less often. Presets: Toward humans, Toward birds, Toward clever octopuses, Toward hive bugs, and Surprise me (random weights). Weights change odds only. A step still has to help its owner survive to spread.
Nudge one line: in the Species tab, pick a species and a step it could gain next, and "Weigh the odds for this line".
Instinct from past worlds: off by default. When on, the first thinker of a kind starts with part of what that kind learned in shared past worlds.
World dials: speed (ticks a second), copy errors, sunlight, plant growth, oxygen push, warmth, sea level. "Reset the dials" puts them back.
Performance readout: under the speed dial, refreshed every second: ticks a second actually running out of those asked for, frames a second, milliseconds per frame for the world and for drawing, labs running, processor threads, and the graphics card name where the browser gives it. A web page cannot read CPU or GPU load in percent. When the computer falls behind the dial it says how many ticks a second it keeps up with, and a "Drop to N" button sets the dial to that.
Fast mode: pauses the picture so a slower computer can run the world faster.
Materials and places: pick one, then click the map: flint beds (toolmakers need them), caves (shelter from cold), fruit trees, lakes, raise land, sink land, plant forest, open grassland. Brush size sets the area.
Pairing: mate choice (nearest, strongest, most alike), hybrids (never, close kin, any near enough), brood size, parent care.
Nature events (the ages)
"Ages come on their own" is on by default: ice ages, extinctions, meteors and so on arrive by the Earth clock (see How real it is). Turn it off and they come only when you call them. You can also fire them by hand: Land plants, Forests, Grasslands, Ice age, Warm age, Meteor, Volcanoes, Flood, Drought.
Meteor: fires on land, then dust that dims the sun. The strike kills about 75% of big bodies, 35% of other many-celled bodies and 5% of single cells.
Ice age: cools the world; ice spreads from cold and high ground and the sea falls. Ice you call by hand is not limited to Earth's ice-age windows.
Volcanoes: ash dims the sun and the world warms for a long age.
Flood / Drought / Warm age: the sea rises over lowlands; rains fail and deserts spread; ice melts back.
A line on the map ("the land now") always says what is changing and why.
The species view and other views
Species tab: living species grouped by kind (fish, worms, bacteria, and so on), most advanced kind first, folded inside kingdom and phylum (a fold you shut stays shut). Tick or untick any kingdom, phylum, kind or living species to show or hide it on the map; each group row has "only" to show just that group, and "Show every kind" clears it. The list holds still: it rebuilds at once after a click, otherwise at most every 30 seconds, never while the pointer is over it, keeps its scroll, and keeps rows in the order they first appeared. A picked species shows its ranks: kingdom, phylum, class, order, family, genus, species. Tap a species for what it can do, its traditions, where it lives in the lab (a 12 x 8 grid), its numbers over time, and who it eats and who eats it. Extinct species are listed below. A "Viruses alive" section lists every living virus family in the order it first appeared: how many creatures carry it, its strains in the water, and since when. "The fossil record" lists each kind in the order it first entered the rock, with its count and the date of its first fossil.
Now tab: "Life over time" (each colour a kind), "Branches of life" (the furthest step each body plan has reached), "Rise and fall" (each step: when it came, how often it was lost, and what ended it), and the world's numbers. Under "The world now", Life by size counts microbes, small bodies and large bodies: how many species of each and about how many creatures. Plants are counted there too. Plant species are named by where they live and what their genes do: seaweed, freshwater algae, land plants, marsh plants, dry-land plants and trees; the Chronicle notes when a line comes out of the water.
Tree of life: a disk drawn like a printed tree of life. First life sits at the centre and time runs evenly outward; a gold axis runs from the centre to the present at 9 o'clock with the dates along it. The circle is shared by rank in fixed places: each kingdom has an equal wedge going round from 9 o'clock (before life, bacteria, archaea, protists, then plants, fungi and animals); inside a kingdom each phylum gets room in proportion to its lines, with gaps between them; an empty wedge stays in place, faint, marked "(none yet)". Each phylum has a trunk, and each line branches off it at its birth with a dot; a lit line shows its true descent in gold. Class names (mammals, fish, insects and so on) sit in italics inside the disk, kingdom names inside their wedges, and the outer ring is coloured by phylum. A "You are here" pointer marks the species you are watching (or else the living line furthest along). Tabs switch the tree: SPECIES, FAMILIES (only lines with granddaughter lines), GENES (living lines grouped by how alike their DNA is, which can differ from descent where genes moved sideways) and VIRUSES (every recorded infection by virus family along a trunk through time: a green dot when the gene worked, red when it was broken, a ring when it was shut out; the last 400 are kept; a living family's trunk reaches the rim, bright and named with its infections and carriers, a gone family stops grey at its last infection; each family's strains branch from the strain they came from, green when the gene works and red when it is broken, the last 300 kept). Species and Families have a LIVING / EXTINCT / ALL row; LIVING is the default and shows only lines that reach the present, with the extinct ancestors they came from as the stem. A Spiral button beside them turns the present into one turn of a spiral (after Hedges et al. 2015): it starts at just over half the rim at 9 o'clock and winds out to the full rim, so more lines fit; off draws the plain circle. The layout is redone at most every 30 seconds, and only when the tree has changed (at once when you switch view), and lines keep a fixed order, so nothing jumps; the GENES grouping follows the same rule, and the VIRUSES tree draws from a 30-second snapshot with virus families in the order they first appeared, never by count. Lines keep their width on screen at any zoom (up to 400 times), and names show along the rim only where there is room. Scroll zooms at the pointer, drag moves, click a line to light its lineage, double-click resets; the + and - buttons zoom, the target button frames the lit lineage, and hovering a line shows a card with the species, its kind, what began it, its dates and its peak numbers. The tree and the Species tab share one selection, and a pick in the Species tab centres the tree on it.
Communities: who lives where in the lab.
Chronicle: the story of the world: firsts, extinctions, events, and your Creator actions.
Saving
The whole world (all 12 labs) is saved in your browser every 60 seconds, when you leave the page, and when the tab is hidden. Nothing is saved on a server. Clearing your browser's site data deletes it.
A second copy keeps the last save whose life was still healthy, so a collapse does not overwrite a living world. When the sim is updated, the old save is also kept as "before the update". Both are in the Creator tab under "Saved copies". There too: "Download this world" writes the whole world, every lab, to one file (genesis-seed<seed>-<lab>-<Ma>Ma.json.gz) to keep or share, and "Open a world file" loads one in place of the running world after asking.
When a new version of the sim goes live, an open page saves the world and reloads itself into the new version within about 10 minutes. It comes back on the same lab, view, zoom, tab and selection, says "Loading your world..." until the save is read, and the Chronicle notes the update.
By default the world keeps running when the page is hidden, at a reduced rate. The Creator tab has a box to turn that off.
Sharing: "Share an anonymous record of these worlds" is on by default. About every 10 minutes it sends what life did in each lab (no personal information) to build the instinct packs. The record also carries your Creator settings: when a setting used in five or more labs beats the defaults without breaking Earth's order of events, it is put forward as a new default, and a person carries it over by hand. Untick it in the Creator tab to stop.
Sending a report
Press B or the ? button. Choose bug, idea or anything else, write it, and add a name if you want. The form shows what is sent with it: the lab, the Earth clock, the tick, the version, the commonest kinds alive, and the creature you are watching (also the view, speed, oxygen and screen size). No address is kept. There is a limit of 10 reports an hour from one sender.
3. How real it is
The project's rule is: as close to real life as code can make it, with numbers taken from published studies. Each number in the sim is marked in the project's sources file as either sourced (from a named paper) or tuned (picked by hand so the sim works). Many numbers are still tuned. Below, each system is split into what follows real science and what is simplified or invented.
Notation: Ma = millions of years ago. Oxygen is given as a share of the air; today's air is 21%.
Time: the Earth clock
From real science
The clock runs real dates from 3,800 Ma to the present, whatever life is doing. Life does not get to skip Earth's three billion years of microbes.
Your world's progress is compared with Earth's dated milestones ("life at ..."): first cells 3,480 Ma, sunlight eating 3,000 Ma, oxygen in the air 2,430 Ma, complex cells 1,800 Ma, many-celled life 1,630 Ma, two parents 1,047 Ma, a front and a back 555 Ma, backbones 518 Ma, land plants 470 Ma, jaws 439 Ma, legs on land 395 Ma, forests 385 Ma, the shelled egg 318 Ma, milk 225 Ma, snakes 167 Ma, feathered flight 150 Ma, grasping hands 66 Ma, walking upright 7 Ma, stone tools 3.3 Ma, speech 0.3 Ma, farming 12,000 years ago.
Simplified or invented
One tick is 2,000 years until 541 Ma, then 400 years, then 100 years from 66 Ma, then 10 years from 2.6 Ma. The present arrives at about 3.7 million ticks. These rates are tuned, not derived.
Earth ran about 1030 microbes for billions of years. The sim runs a few thousand creatures. No honest "years per generation" is possible, so the clock and life's progress are shown side by side and often disagree. A more honest clock, based on the real waiting time for each change, is described in the docs but not built.
Evolution does not stop at the present. Past it the clock reads "present + N years" and keeps going, at 100 years a tick once it is more than 100,000 years past today.
DNA and evolution
From real science
Bases A, C, G and T. Every copy can miscopy any base; pairs mix their parents' DNA (crossover).
Many-celled bodies copy their step genes more carefully than single cells (a germ line, after Weismann 1892).
Complex features arise through partial steps that already pay a little (Lenski et al. 2003; Nilsson and Pelger 1994 for eyes). A gene 2 bases from a working step gives a quarter of its effect.
Eyes get no aimed mutations (that dial was taken out on 5 October 2026, as real mutations are not aimed); they come from an eyespot and a light patch that already pay.
Eyes come by a ladder where every small step pays (Nilsson and Pelger 1994): a light-sensitive patch (an eye gene three bases off) pays a tenth of an eye, an eyespot (two bases off) a quarter, and both pay in any many-celled animal, as in jellies and sponge larvae (Nilsson et al. 2005; Arendt 2003); full eyes still need a front and back.
Genes pass sideways between microbes (up to about 17% of E. coli's genes came that way: Ochman et al. 2000).
Species split by DNA distance; pairing depends on how different two bodies' DNA is (Coyne and Orr 1989), with limits measured from the sim's own species.
Two clusters in one name: the members of a species are sorted into two DNA groups, and the smaller becomes a new species when the groups are far enough apart and each is tight. The line is lower for lines that copy themselves without a partner, as in bacterial ecotypes (Cohan 2001; about 95% genome likeness: Konstantinidis and Tiedje 2005).
Splits by distance (allopatric speciation): a species living in two groups with an empty stretch between them splits once their genes begin to differ. The size of the gap (15% of the lab) is tuned.
Instinct is wired from the DNA; what a mind learns in its life dies with it unless passed on by imitation, teaching or culture.
Simplified or invented
Each creature has four strands: body dials (2 bases each, a value from 0 to 15), mind dials, one 7-base gene per step of life, and an instinct strand. Since 5 October 2026 every creature carries two copies of each step gene, one from each parent; the better copy counts (a working gene is dominant). The body dials (size, speed, diet, poison and the rest) also come in two copies, one from each parent, and the body reads the middle of the two: both copies show, as A and B both show in AB blood (codominance).
Viruses carry genes between lines. A disease death releases virions holding one of the dead creature's step genes; they copy that gene with errors, so each virus family holds strains a base apart, some carrying a working gene and some a broken one. A virus written into a creature stays in its DNA and passes to its young, and a carrier is shut to the other strains of that family, so one strain can keep out a harmful one (superinfection immunity: Bertani 1953, Lwoff 1953; the same idea as CRISPR memory in microbes).
A gene can jump. A working step gene may become a transposon: at a birth it copies itself, with the usual errors, to a new place in its own genome, about once in fifty births. The copy lands as a spare copy (a backup, a dose, or a copy free to take a new job) or, once in twenty, inside another gene, where the second copy hides the damage. The element is born when a working gene is duplicated, is lost now and then, passes from one carrier parent to half the young, and is the gene most often carried out when a virus bursts from its carrier, so a jumping gene can escape into a virus and arrive in another line with its mobility. After BC200, a primate brain gene that kept jumping for forty million years and turned up inside a human poxvirus (Gao, Pritham, Feschotte and Sun 2026).
A step works when its 7 bases spell a set sequence (one base off still works) and the steps it builds on work. This is a game device. What each step does is written by hand, so nothing can evolve that is not on the list. An outside review (3 October 2026) called this the biggest gap; turning steps into continuous body-part dials has started (shell thickness, armour, jaw strength, eye quality, fin size).
Copy errors are 0.004 per base per copy, with step genes miscopied 4 times as often. Real rates are far lower (humans about 1.2 x 10-8 per base per generation: Kong et al. 2012). The sim needs high rates because it has vastly fewer creatures and generations.
Guided weights are a game dial, not nature.
The steps of life (the chart)
The live page has 32 steps: a membrane, sunlight eating, complex cells, two parents, many cells, a front and a back, a shell, armor and jointed legs, a backbone, tentacles, jaws, eyes, breathing air, fleshy fins, walking legs, the amniote egg, losing the legs, feathers, warm blood, fur, milk, wings, a beak, venom, grasping hands, opposable thumbs (a thumb that meets the fingers; it needs hands), living in groups, a big brain, a rich voice, walking upright, teaching the young, and speech.
Most steps have several routes: eyes on a worm, a backbone, tentacles, armor or a shell; legs from fins, armor or tentacles; wings from feathers, fur, bare skin or armor.
Body plans exclude each other: a backbone, armor and tentacles cannot be combined; fur and feathers cannot; a legless body cannot have wings, hands or walk upright.
The kind of life (fish, reptile, bird, ape, and others) is named from the whole set of steps a line has. Some combinations give kinds Earth never had, such as "armored graspers" or "a people never seen".
Stone tools, fire, song, hives, dams, farming, villages and towns are traditions a species discovers from its abilities and surroundings, kept alive by teaching and speech. They are not genes.
Minds grow with the body, in 8 tiers: chemical reflex, nerve net, reward learning, memory, drives, imitation, big brain, culture.
Each step from a front and a back up to milk was tested on 4-5 October 2026 by planting animals into a saved world (not grown from scratch): each one paid or held its own, the shell least. Whether a fresh world reaches them unaided is still being watched.
Oxygen
From real science
The early air starts with almost no oxygen (about 2 parts per million; Archean air was under 1/100,000 of today's: Pavlov and Kasting 2002). Volcanic gases and iron remove oxygen until 2,400 Ma.
Oxygen is a budget: buried dead matter and coal add it; weathering, fire and (early on) volcanic gases take it (Berner and Canfield 1989; Berner 2006). The Great Oxidation happens when burial outruns the sink. Land plants raise oxygen further by burying carbon (Lenton et al. 2016).
Oxygen is also a poison. Every cell starts with no tolerance for it; above about 0.5% of today's level in its own water it takes damage that grows with the oxygen, and tolerance has to evolve, at a small upkeep cost (Imlay 2013; McCord, Keele and Fridovich 1971). Deaths from it are logged, the first as OXYGEN THE POISON. Low-oxygen water (deep, rotting) stays a refuge.
A cell gains the nucleus only when its water holds some oxygen; its breathing gain ramps up around the Pasteur point (about 1% of today's level).
Animal size is capped by oxygen: growth starts at 0.2% of the air (sponge-grade animals: Mills et al. 2014), full size at 21%, larger toward 30% (the giant-insect era).
Each patch of water has its own oxygen: warm water holds less (14.6 mg/L at 0 C against 7.6 at 30 C: Benson and Krause 1984), deep water has none until the air holds about 3-10%, and rotting patches run short.
Warm water raises a cold-blooded animal's oxygen need (the metabolic index: Deutsch et al. 2015).
Wildfire needs at least 15% oxygen (Belcher and McElwain 2008).
Air-breathing animals use air oxygen when the water runs short, as lungfish do (Graham 1997).
Simplified or invented
Each lab keeps its own air. On Earth the air is one shared atmosphere. Most labs sit in the dry belt near 30 degrees, so a lab's oxygen tends to settle below 21%.
The rates of burial, weathering and coal are tuned. There is no carbon dioxide or methane in the air yet.
Temperature and warm blood
From real science
Cold-blooded life runs faster when warm: feeding, upkeep, rest and growth follow the Boltzmann factor with 0.65 eV (Gillooly et al. 2001), about 2.5 times per 10 C. Sun-eaters are left out of this rule.
Warm-blooded animals keep near 37 C and feed at that pace: about 3.4 times the 22 C reference. They also pay for it: upkeep is about 12 times a reptile's for mammals and 20 times for birds, narrowing with size (Nagy 2005).
Labs at different latitudes evolve differently. In shared run records (5 October 2026), tropical and warm labs held a median of 9 living species against 1-4 in temperate, cold and polar labs, as on Earth (the latitudinal diversity gradient: Hillebrand 2004); most of those cold labs had run only briefly. Body size, fur and seasonal storage by latitude are being measured as records come in.
Temperature by latitude follows Earth's yearly average: about 26.5 C at the equator, 19 C at 30 degrees, 5 C at 50, -2 C at 60, -25 C at the pole.
In an ice age, land near the poles cools far more than the tropics (Tierney et al. 2020).
Small warm-blooded animals can go into torpor in the cold, burning about 30% of their usual upkeep (Geiser 2004). Bigger warm bodies hold heat better (Bergmann's rule). Cold-blooded animals grow smaller in warmer water (the temperature-size rule).
Ocean currents carry heat; cold, nutrient-rich water wells up off some coasts.
Simplified or invented
The 22 C reference point is a calibration chosen so the tuned rates keep their meaning.
Currents in the sim stand in for the winds that drive real upwelling.
Seasons last 1,200 ticks and tides 400 ticks: these are for the picture, not real time.
Food, bodies and metabolism
From real science
Energy use scales with body mass to the 3/4 power (Kleiber; West, Brown and Enquist 1997); lifespan and growing up scale with mass to the 1/4.
Young are born small and grow along a measured curve (West et al. 2001). Parents split their energy between more young or bigger young (Smith and Fretwell 1974).
Big bodies store more and go longer between meals (fasting endurance scales with mass to 0.44: Lindstedt and Boyce 1985).
Food comes in sizes: single cells take dissolved matter and small plankton; animals take large plankton, which grows only in rich water (Sheldon et al. 1972). Hunters take prey 0.12 to about 1 times their own size.
Green land sheds 0.1% of its plant matter at a time as leaf litter into the dead matter on the ground (Bray and Gorham 1964), and fungi feed on it.
Under the ground: mud buried on the sea floor turns to kerogen, then oil and gas (half of it within 10 million years of Earth time, the oil window); wood in wet forests turns to peat, then coal; bodies that die unwashed in still deep water, lakes or swamp forest are kept as fossils 2% of the time, counted by kind. The Now tab shows it in a row called "Under the ground", and the first oil, coal and fossils are logged as firsts.
Bacteria do the rotting (the microbial loop: Azam et al. 1983); 13% of what sun-eaters make leaks into the water as food for bacteria (Baines and Pace 1991). Dead plankton sinks as marine snow, less reaching deeper floors (Martin et al. 1987).
Plant-eaters need gut bacteria, inherited half from the mother; without them seaweed and land plants pay only 30% (Bergman 1990).
Hunters find prey as often as they meet them, so catches get harder as prey grows scarce (Holling 1959). A hunter that has just caught one kind hunts for that kind: it carries a search image, and sees other prey only closer in (Tinbergen 1960; Pietrewicz and Kamil 1979), so it switches to whatever is common and leaves the rare alone (Murdoch 1969). Nothing is safe by rule: a line can be hunted out, though it rarely is.
Tools come first and diet follows: an animal with jaws, venom or tentacles starts hunting at a lower meat share than one without.
Without a weapon (jaws, venom, tentacles, claws), a hunter can only take small prey, up to about 0.4 of its own size (about 6% of its weight), as jawless fish and other engulfing feeders do (Brose et al. 2006; Hambright 1991). Large active hunting in backboned animals came with jaws (Anderson et al. 2011).
Small prey are seen late: a hunter notices prey from a distance that grows with the prey's size (Werner and Hall 1974; Confer et al. 1978). Prey half the hunter's size or bigger is seen at full range; smaller prey only closer in, down to a quarter of the range. This is much of why small animals escape big hunters and stay the many.
A water-bound body (no air breathing, no wings) left on dry ground by a falling sea, the tide or a growing map flops toward water and dies "stranded" after a short time out, as gills collapse in air (Graham 1997); the damp tidal strip is safe for everyone, so the tide does not strand shore life.
Learning from reward comes with a head, not a backbone: a backbone, eyes, or armour on a body with a front and back (arthropods) all bring it, as it arose in the Cambrian in vertebrates, arthropods and cephalopods alike (Ginsburg and Jablonka 2019). Bone has an upkeep cost, as shells and armour do (Currey 2002).
Every real land animal with a backbone descends from jawed, lobe-finned fish; no jawless vertebrate ever came onto land. The sim does not forbid that road, so a world may take one Earth never did.
Some lines hunt each other (intraguild predation: Polis, Myers and Holt 1989); the species card marks them "both ways".
Hunters pick the easiest catch (young, starving, small); prey can wound hunters; camouflage, countershading, warning colours, poisons, thorns, shells, burrowing and alarm calls all work as defences.
An alarm call protects the ones who hear it, not the caller: kin who hear it are warned and defend better while it lasts, and the caller is easier for the hunter to pick out (Sherman 1977). Killing a rival's young to bring the mother back into breeding is done by males, in milk-feeding lines (Hrdy 1979).
Young are weaned when they have grown big enough, not after a fixed time.
Disease rises with how often kin meet: each nearby kin dot counts by how many creatures it holds and how far they roam (density falls with body mass, home range grows with it: Damuth 1981; Jetz et al. 2004), so it hits the commonest kin hardest; parasites, immunity, coral partners, root fungi, pollinators and two sexes with mate choice and male fights are in.
Hot vents on the deep sea floor feed life without sunlight.
Simplified or invented
Each dot on the map stands for a crowd. The sim keeps about 700 dots per lab and changes how many creatures each dot stands for ("N dots, each about M creatures"); big animals' dots stand for fewer than small ones' (density falls with mass: Damuth 1981). This is the computer's budget, not nature's.
The same food for any size: across Earth's animals, a population uses about the same energy whatever its body size; many small bodies eat what a few big ones do (energetic equivalence: Damuth 1981; Kleiber 1932). Each dot eats as its creatures would, so a dot of small worms is no longer charged several times what a dot of big animals is. How fast a line breeds is set by its genes, never by its size.
Energy goes by mass: a hunter gains what its prey's body and stores are worth by weight, less what is lost in digesting, and a meal ends when the hunter is full, not after a fixed number of prey. A carcass feeds the ground by the mass of the creatures that died. Filter feeders, grazers, fruit eaters, cells that swallow cells and parasites all trade energy by mass the same way (before, a filter feeder was paid about 11 times what it took).
Every tick holds whole years (10 to 2,000 of them), so every tick holds its summers, winters and tides. Temperature is the year's mean; a body must get through the winter, and its cold cost is the average of its winter and summer shortfall; ice that forms only in winter darkens the sea half the year. A year-round breeder loses half its young where the winter is too cold for them; a seasonal breeder waits for spring.
Disasters come and last by real years: ice pulses about a million years apart inside an ice-age window (Fielding et al. 2008), sea-level high stands every few million years (Haq et al. 1987), warm spikes about 200,000 years long like the PETM (Rohl et al. 2007), droughts, meteors and flood basalts. There is no quiet start: the young Earth gets its share.
Outside the ice ages the climate swings with the orbit's steadiest beat, a 405,000-year cycle worth about 1 C (Laskar et al. 2004; Westerhold et al. 2020).
Plants stay where they grew, on land and in water (a seaweed holds fast by its holdfast), and have no mind: they don't choose acts. A plant that breeds in pairs does so at a distance, by pollen or released gametes. A plant in water is a seaweed or freshwater alga; land plants grow on land. A plant species is named by where its members live from birth, not by its genes alone: a line born in fresh water is a freshwater alga even if its genes lean toward trees.
Nutrients move with matter: a cell that dies in water gives back its nutrients at once (and its contents to the dissolved pool), a body rots and returns its nutrients through the dead matter, and every creature takes up nutrients by its whole mass.
Flowering plants are not switched on by date: they arrive when enough land plants bear fruit.
The wait between broods is in the genes, not the body size: a line built to live long breeds less often, a short-lived line more often (the fast-slow continuum: Stearns 1983; Promislow & Harvey 1990).
A plant defends itself when it is bitten: a bitten seaweed or land plant raises its poison and thorns for a while and pays for them only while they are up, and its own kind in the same patch raise theirs by half as much before they are bitten (induced defence: Karban & Baldwin 1997; Baldwin 1988; signals to kin: Baldwin & Schultz 1983; Karban et al. 2014).
Land plants with root fungi share through them: now and then two in the same patch even out a little of the difference in their stores, and the fungus keeps a toll. It is kept small because how much it matters is argued (Simard et al. 1997; Karst, Jones & Hoeksema 2023).
A land plant sleeps through the cold: the part of the year colder than it can stand earns no light and costs a tenth of its upkeep, with no frost damage; it grows in the warm part of the year (winter dormancy: Rohde & Bhalerao 2007; growing season: Churkina et al. 2005).
No nutrients, no growth: plants and plankton grow only as far as the nutrients in their patch allow (Liebig's law of the minimum); there is no floor.
Rivers reach the sea: rain runs downhill and every hollow fills until it spills, so rivers join into branching systems that end in the sea or in a lake; a lake in a dry land with no outlet is a closed salt basin. The region is a window on a bigger land, so big rivers flow in from the country beyond its edge (depression filling: Barnes, Lehman & Mulla 2014). The rivers follow the sea level of the day.
Weather moves: wet and dry spells drift across the land over the years, on top of each place's usual rain by latitude, so deserts spread and shrink and rivers and their runoff rise and fall with them. Rain wears soil off bare ground, faster on steep slopes and in wet spells; plants hold it.
Rivers feed the sea where they meet it: the nutrients washed off the land come out at the river mouths, more from a bigger river, and spread in a plume that fades offshore, as real river plumes feed coastal blooms.
Rivers flow: whatever drifts in a river is carried downstream toward the sea, faster in a big river and three times as fast in a flood (stream drift: Muller 1954; Waters 1972). Fish hold their place by swimming against it; crawlers on the bed drift less.
The open sea: the region's sea is one corner of an ocean the region cannot empty. Every line living in the region's sea lives out in the open sea too, and the water coming in across the edge keeps carrying some of them in, whatever happens inside. A coast emptied by a die-off fills again from offshore, as real coasts do (the rescue effect: Brown & Kodric-Brown 1977; supply from offshore: Roughgarden, Gaines & Possingham 1988). A mass extinction strikes the open sea too, but never takes its last sun-eater: the ocean's plankton came through every one (Bown 2005).
The map's edge is not a wall in the sea: water the current carries out is replaced by water flowing in elsewhere along the edge, carrying the same plankton, so drifters don't pile up against the border.
Single cells drift wherever the water goes: they swim micrometres a second against currents of centimetres. Microbes are everywhere, and their lines part by what they live on (Baas Becking 1934).
The long Cenozoic drying comes from the climate (Zachos et al. 2001), from 50 million years ago, and grasslands spread because of it; grass does not dry the world.
Life starts once. Replicators spark in the warm shallows only until the first cell; after that life eats the soup and never starts over.
Mutations are not aimed (Luria and Delbruck 1943). Eyes come early because every stage pays on its own: an eyespot, a cup, a lens.
A virus written into the DNA sits on one parent's chromosome, so half the young of one carrier get it.
Reptiles, birds and mammals can go back to the sea (they did at least 30 times): a body built for swimming, with flipper-like limbs, lives in deep water and breathes air. Egg layers come ashore to lay, as turtles do; live bearers breed at sea, as whales do.
Nothing with a backbone clones itself; mammals cannot. A backboned line that cannot find mates dwindles.
The wider world beyond the map is real too: the same trickle of newcomers whatever the region's state, lines out there die out as real species do (a few million years), and a returner has drifted by the generations it spent away.
Routes follow what life did: no octopus breathes air or walks on land; venom can arise in any animal (it arose over 100 times, first in jellies); every air-breathing backbone can evolve a voice, frogs too.
Aerobic bacteria get the same yield from oxygen as the mitochondria that came from them; the nucleated cell's edge is the energy per gene that pays for its bigger genome.
A seed bank keeps microbes from vanishing, one for bacteria and one for complex cells (so plenty of one cannot hide the loss of the other): while 20 or more cells of a layer live, each lab stores the DNA of up to 8; if fewer than 20 are left, 5 wake in the water every 200 ticks. A lab whose bank is empty fills it from single cells living in another lab, or, when no lab has any, from those that left the map into the wider world, ("everything is everywhere, but the environment selects": Baas Becking 1934; de Wit and Bouvier 2006). This stands in for dormant cells and spores; the numbers are tuned.
Many amounts are tuned: upkeep base, bite sizes, the strength of each defence, disease odds. How long a search image lasts (300 ticks) and how much closer other prey must be (0.6 of the reach) are tuned.
The ranks are the game's own. Kingdom, phylum and class come from the steps a line has (Bacteria, Protists, Plants, Animals; Chordates, Arthropods, Molluscs and so on; Mammals, Birds, Fish, Insects and so on). Order, family and genus are named for the lines a species branched from, so sister species share a genus.
Bodies range over a far smaller span of sizes than real life.
Creatures are drawn jiggling about their place at high speed. That is for the picture only; the sim does not read it.
Climate, ice and the land
From real science
Ice ages open in Earth's real windows: 2,430-2,220 Ma (Huronian), 445-440 Ma (end-Ordovician), 360-260 Ma (Karoo). Two snowball glaciations at 717 and 640 Ma (Sturtian and Marinoan), with a nutrient pulse after the melt that feeds algae.
From 2.6 Ma, ice comes in cycles: about 41,000 years until 1 Ma, then about 100,000 years (a long slow cold, a fast warming, a short warm spell) (Lisiecki and Raymo 2005). The Antarctic ice sheet arrives at 34 Ma. The Paleocene-Eocene heat comes at 56 Ma.
Sea level follows Earth's long-term curve from 541 Ma (high in the Ordovician and Cretaceous). Rain follows latitude: wet tropics, dry belts near 30 degrees.
The supercontinents stand at their real dates (Kenorland 2,700-2,400 Ma, Columbia 1,800-1,300, Rodinia 1,100-750, Pangaea 335-175). While one stands, life crosses freely between neighbouring labs; between them, few get across. When ice ages lower the sea, land animals cross between neighbouring labs more easily over land bridges (about 120 m of sea fall at the last glacial peak: Clark et al. 2009; Beringia: Hopkins 1967; Sundaland: Voris 2000); swimmers get no help. The first is logged as LAND BRIDGES.
Rivers run downhill by the steepest fall and join into branching networks; no river ends in a dead-end pit. Water creatures in a river swim along it, up or down the flow, so river life spreads through the river system between floods.
Soil builds at real soil-production rates under plants, twice as fast under forest, and is stripped from bare ground and under ice.
Forests begin when tall land plants are established (first forests 385 Ma on Earth). Flowering plants come at 130 Ma. Grasslands open from 8 Ma, or after 55 Ma where the world is dry enough. The green on the land follows the land plants that are actually alive: when none live, it fades.
Simplified or invented
Continents do not move on the map. Only the 12 labs are simulated; the rest of the planet exists only as the globe picture.
The strength and length of each cold, and the odds of floods, droughts and warm ages, are tuned. A slow climate swing of 18,000 ticks is tuned.
Extinctions and disasters
From real science
The Big Five fire at their real dates with their real causes: end-Ordovician ice (445 Ma), Late Devonian ocean oxygen loss (372 Ma), end-Permian eruptions (252 Ma), end-Triassic eruptions (201 Ma), and the end-Cretaceous impact (66 Ma). Three smaller events also fire: 260, 183 and 94 Ma.
Whole kinds die by their traits and range. Tuned against Earth's species losses (86, 75, 96, 80 and 76%: Barnosky et al. 2011), test worlds lose an expected 80, 71, 91, 79 and 79% of their many-celled kinds.
Large meteors come about once per 100 million years (Chapman and Morrison 1994); flood-basalt eruptions about once per 25 million (20-30: Ernst and Youbi 2017). An impact's darkness lasts years, not ages (Toon et al. 1997). The big die first; microbes mostly ride it out.
Simplified or invented
The kill odds, strengths and lengths of each event are tuned. The test worlds behind the 80/71/91/79/79 figures held only 2 to 6 many-celled kinds, so those figures are rough.
Earth's disasters arrive on the clock even if your world's life is far behind Earth's.
4. What is not in it, and what is still to be done
built in the live sim partly built a first version exists planned on the list, not live not planned left out on purpose
Item
Status
Notes
Opposable thumbs on the chart
built
Added 5 October 2026: a thumb that meets the fingers, after grasping hands, on the route to tools and humans. The chart was widened past 32 steps to make room; old saves load unchanged.
Plate tectonics
partly built
The supercontinent cycle controls how easily life crosses between labs. Land bridges in ice ages are in (5 October 2026). Not yet: land moving on the map, named one-time gateways such as Panama (the planet is generated, not Earth), sea level from spreading ridges.
Mass extinctions on Earth's schedule
partly built
The Big Five and three smaller events are in. The Great Oxidation now poisons cells that have not evolved oxygen tolerance (5 October 2026). Not yet: a gamma-ray burst, more small extinctions.
Fungi and archaea
built
Fungi are in (5 October 2026): a many-celled line that does not eat sunlight, has no front or back and suits dry ground becomes a fungus, roots on plant ground, feeds on dead matter through its mycelium, gives 30% back as nutrients, and has its own kingdom on the tree. Archaea are in too: when the first complex-cell line branches, the simple-cell line it came from founds the archaea, and every simple-cell line descended from it is an archaeon (complex cells grew out of archaea: Eme et al. 2017; Zaremba-Niedzwiedzka et al. 2017). The tree has seven kingdom wedges.
A fossil record view
partly built
The Species tab lists the fossil record by kind, in the order each first entered the rock (5 October 2026). Not yet: browsing single fossils or rock layers.
Trees of species, families, genes and viruses
built
Added 5 October 2026 (after Hedges and Kumar 2009, Hedges et al. 2015, Hillis 2008). The spiral layout of Hedges et al. 2015 is in as a Spiral button.
The pyramid of life (more microbes than bodies, more grazers than hunters)
partly built
Each shared run record now counts every layer and the report marks a layer bigger than the one under it. Known problem (5 October 2026): in the furthest-along worlds, single cells can all but vanish once bodies take over. The seed bank is the first fix, and an empty bank now refills from another lab: in a test world with no cells left, bacteria came back and held at about 4,500-6,000 creatures for 5,000 ticks beside the animals.
Plants
partly built
Seaweed lines can root on land; land spread, forests, flowers, soil, root fungi and pollinators are in. Not yet: flowers and pollinators evolving together.
Arms races between hunters and prey
partly built
Speed, armor, camouflage against eyes, poison and poison-proofing, fighting back.
Climate and the air
partly built
Ice ages, cycles, latitude, rain, sea level and an oxygen budget are in. A greenhouse model now runs in the shadows (5 October 2026): each lab works out carbon dioxide and methane from its own life, a Sun 25% fainter at the start (Gough 1981), the weathering thermostat (Walker, Hays and Kasting 1981) and ice reflecting sunlight, and records the result, but the scripted climate still sets the temperature until the records show the model tracks Earth. As it stands it leaves the early Earth too cold (the faint young Sun paradox) and makes no snowballs. Not yet: ocean acidity.
Caves, hot springs and salt lakes as separate habitats
partly built
Hot vents are in; caves exist only as shelter.
Jumping genes
built
Added 13 October 2026 (after Gao, Pritham, Feschotte and Sun 2026; rates after Kazazian 1999 and Ewing and Kazazian 2010). A working step gene can become a transposon that copies itself to new places in its own genome at a birth: as a spare copy, or over another gene on one chromosome. It rides out in virus bursts and arrives with transduced genes. The creature panel names a carrier; the world logs the first jump and the first escape.
Viruses
partly built
Disease hits the commonest kin, and genes pass between cells. Viruses now carry genes: a disease death releases virions holding one step gene; strains differ by a base, some good, some broken; a carried virus is inherited and shuts out other strains of its family; a virus family stays alive while any creature carries it in its DNA, not only while strains drift in the water. A single cell carrying a virus now and then wakes it (about once in a thousand cell lifetimes: spontaneous prophage induction, Nanda et al. 2015), bursts, and spills strains wherever it has wandered, so virus families travel with their carriers; viruses in bodies stay asleep. Most infections only settle the virus into the cell's DNA (lysogeny); only about 7 in 100 also write the virus's gene over a gene of the cell (transduction). With that split, about a fifth to a third of cells carry a virus after 10,000 ticks and the share is still climbing toward Earth's half (Touchon et al. 2016). The infection odds are tuned. Not yet: epidemics spreading between labs.
Hives and sterile workers
built
Animals feed hungry kin when it pays (Hamilton's rule). Sterile workers are in (5 October 2026): a caste dial lets a mother living in groups with two parents raise some young as workers, who never breed and feed her and her hungry young (Hamilton 1964; Wilson 1971; Hughes et al. 2008, monogamy first; Nowak, Tarnita and Wilson 2010 dispute the kin explanation). Whether castes pay in long worlds is still to be seen.
Language
partly built
Alarm calls and the speech step are in. Not yet: different calls for different hunters, symbols.
Culture and technology
partly built
8 fixed traditions (stone tools to towns). Not yet: open-ended technology built from combinations of abilities, or named traditions such as songs and routes.
Chronicle cards
partly built
Firsts, extinctions with their span and commonest cause, and convergent evolution are logged. Not yet: lineage titles, extinction obituary cards, first-of-kind cards.
Steps as continuous body parts
partly built
Strength dials for shell, armor, jaws, eyes and fins are in; the steps themselves are still switches.
Breed mode (pick who survives)
planned
On the list, not started.
Steward mode (save an endangered species)
planned
On the list, not started.
Compare runs (seed against seed)
planned
On the list, not started.
A calibration test against Earth's order of events
planned
Many seeds scored against Earth's timeline. Not built.
A clock based on real waiting times
planned
Described in the docs as the honest clock; an open decision, not built.
Faster code
planned
A rewrite of each creature's turn for speed, then the world on its own processor core. About 250 ticks a second is the current limit on one core.
Cutting detail to run faster
not planned
The owner's ruling (4 October 2026): no detail is removed for speed.
Making or placing creatures by hand
not planned
A design rule: the player shapes the world and the odds, never the creatures.
A single fixed road to humans, or a tech tree
not planned
Replaced on 28 September 2026 by steps with several routes and by traditions.
A head count that decides who lives
not planned
Removed on 3 October 2026: food, light, predators and disease set the numbers.
One known oddity: each creature is drawn in the colour of its own DNA colour dial, so one kind can show several colours at once.
5. Glossary
Earth clock
Real time in your world, from 3,800 Ma to the present. It runs on its own.
Life at / Earth stage
The date on Earth's timeline that matches the most advanced milestone your world's life has reached.
Ma
Millions of years ago.
Tick
One step of the simulation. Its length in years depends on the era (2,000 years early on, 10 years near the present).
Generations (gen)
Generations of all life so far. "Longest line" is the longest single line of descent.
Speed, "600 (running 150)"
The speed dial also says how much Earth time that is, e.g. "60 = 120,000 years a second" (ticks a second times years a tick). The ticks a second you asked for, and in brackets the ticks a second your computer is actually managing.
Dot, "N dots, each about M creatures"
Each dot on the map stands for a group of creatures when a lab is crowded, and eats and breathes as that many would.
Lab
One of the 12 simulated places on the planet. Also called a region on the map.
Step (of life)
An ability such as a membrane, jaws or warm blood, carried as a 7-base gene. It works when the gene spells its sequence and the steps it needs are present.
Kind
The kind of life a line is (bacteria, jellies, worms, fish, reptiles, apes and so on), named from its full set of steps.
Species
A group of creatures that can pair. New species branch off when a group's steps or DNA drift far enough from the rest.
Replicators
The self-copying molecules of the early soup, before cells.
Sun-eaters
Life that makes food from light (bacteria, complex cells, seaweed, land plants). They make the oxygen.
Complex cells
Cells with a nucleus, built around a partner cell they took in.
Jellies
The sim's name for simple many-celled bodies with no front or back.
A front and a back
A body with a head end and a gut (worms). Every later animal body plan needs it.
Oxygen, "% of the air"
The share of the lab's air that is oxygen. Today's Earth is 21%.
The ages
The large events: land plants, forests, grasslands, ice ages, warm ages, meteors, volcanoes, floods, droughts.
The Big Five
Earth's five largest mass extinctions, which fire at their real dates.
Traditions
Learned ways of life a species can discover and pass on: stone tools, fire, song, hives, dams, farming, villages, towns.
Free / Guided
Free: every copying error is chance. Guided: your weights tilt where copying errors land.
Weight / Nudge
A weight tilts the odds for a group of steps everywhere; a nudge tilts the odds for one species toward one step.
Instinct from past worlds
An option (off by default) to start a kind's first thinkers with part of what that kind learned in shared past worlds.
Branches of life
The furthest step each great body plan has reached right now.
Rise and fall
For each step: when it came, how often it was lost, and what ended it.
Closest to human
The living species with the most of the 23 steps on the route to humans.
Chronicle
The written history of your world, including your own Creator actions.
Wider world / left the region
Creatures that left the lab. Some return later as newcomers.
Fast mode
Pauses the picture so the world runs faster on a slower computer.
6. God's hand: how the rules came to be
None of these rules arrived right first time. CODER and BLACK change how the world works almost every day: a world shows something wrong (a sea that stays empty, a group that takes over, a rule that only made the numbers look good), we find the cause, change the rule, measure it on saved worlds, and keep it, take it back, hold it, or park it. God's hand shows every one of those changes, newest first, with what we saw, what we changed, how it measured and how it went, and links each change to the earlier ones it follows on from. It is rebuilt from the work log and the code history with every release, so it is always current.