NatureSim: a meadow ecosystem

Grass and bushes grow across the meadow, fed by fertility that comes from rabbit poop and decomposing carcasses. Rabbits must independently balance hunger, thirst, sleep, territory, and reproduction — there's no scripted choreography, only individual needs and a day/night clock.

Needs & limits: each rabbit's hunger and thirst climb steadily and must be relieved by grazing/drinking. A single feeding bout can only relieve so much hunger (a stomach-capacity cap) before the rabbit must digest and come back later. Every rabbit tries to eat, drink, and poop (marking territory near its burrow) at least once before nightfall; if it spent the day on other business — mating, defending territory, building a burrow — it scrambles to cover survival needs in the evening instead of sleeping hungry.

Founders: the simulation starts with 55 females and 40 males by default — a much bigger seed than a wolf-free meadow needs, to give the rabbit population a buffer against predation. Females are the reproductive bottleneck (gestation ties one up for several days per litter, while a male can father several litters in that time), so a female-leaning ratio grows the population faster early on. The founder count matters more than the ratio for long-term survival: each rabbit carries a small genome, offspring inherit a blend of both parents' genes, and mating between close relatives produces smaller, less viable litters. You can experiment with different founder counts using the restart controls.

Wolves: three clans hunt the meadow — Redfang and Frostmane are rivals that fight at territory borders, while Greywood stays neutral toward both. Each clan dens in a hillside cave and shares it communally. Wolves run the same needs/aging/reproduction rhythm as rabbits, but hunt rabbits for food instead of grazing, and can fast for well over a week between kills the way real wolves do. A wolf chasing a rabbit needs sustained close contact to make the catch — a rabbit with more stamina left than its pursuer usually wriggles free, so chases don't always end in a kill. Both species share a fatigue system: sprinting (fleeing, chasing, or fighting) drains stamina, which only recovers at a walk or asleep, so an exhausted animal has to rest before it can run hard again. Rabbits are instinctively afraid of nearby wolves and will drop whatever they're doing to flee. Wolf clans breed within their own clan when possible but will travel to find a mate elsewhere if their own numbers run thin, and if a clan is ever wiped out, a stray wolf occasionally wanders in from outside the meadow — mirroring how real regional wolf populations aren't fully sealed off from each other.

Pack hunting: a hungry wolf that spots prey will often call in one or two nearby packmates to join the same chase instead of hunting alone. Two or three wolves converging on the same rabbit close the gap much faster than a lone hunter could, and the kill (and the meal) is shared between them — this is what cuts down on wolves starving after a string of failed solo chases.

Weather: rain rolls in at random and lasts several hours to most of a day. It speeds up grass growth noticeably, eases thirst for every animal (wet vegetation and puddles), and makes it harder for wolves to spot prey at a distance — so a rainy stretch is generally good news for the meadow and a mixed bag for hunters.

Passing herds: every few days a herd of elk, moose, or caribou wanders through the meadow for a day or so. They're much tougher than a rabbit — a lone wolf can rarely bring one down before giving up exhausted — so a hungry wolf that spots the herd will rally nearby packmates to hunt it together, and while the herd is around, wolves generally go after it instead of rabbits (bigger, easier calories). A successful group kill is a huge, generously shared meal. The log names every wolf involved and which clan they're from, so you can watch a real pack hunt unfold. A few birds also drift across the sky now and then — purely for atmosphere, no effect on anything.

Population control: rabbit growth is capped by grass/bush regrowth and water access, plus old age, starvation, dehydration, overcrowding stress, and now predation. When rabbits get very scarce they also become disproportionately hard to find (a "prey refuge" effect), which is what stops a large wolf clan from hunting the meadow bare. Wolf numbers are capped by prey availability, territory fights between rival clans, and their own overcrowding stress — so both populations oscillate rather than growing forever or collapsing.

The worker: resources, tools, and buildings belong to a persistent colony, not to any one worker -- hiring one costs wood/stone/fiber from the colony stockpile (shown in the Colony panel), paid up front. With no worker and nothing banked yet, use the +Wood/+Stone/+Fiber buttons to gather a little yourself until you can afford the first hire -- or click directly on a tree, rock, or patch of grass on the map to gather from it by hand. Once dropped, he needs to eat, drink, and relieve himself, and everything he does -- gathering, crafting a spear/torch/rope, building a shelter, farming, hunting, trapping, breeding, processing goods, and selling to a merchant who visits every 15 days -- takes real time and materials, all banked into or drawn from that same stockpile. You don't control him directly: you fill six task slots (three priority, three secondary) from a dropdown, and he works through whichever queued task is both selected and currently possible, checking priority slots first. Wolves are not afraid of him and will attack if he's unarmed or wanders too close to a den; a spear or torch cuts the damage and gives him a real chance to fight back. Rabbits are wary of him but will always raid an unfenced garden, and wolves will raid an unfenced breeding pen. If he dies, the colony's stockpile and buildings are untouched -- gather or bank enough to pay the hiring cost again and drop a replacement. His run (and the whole colony) is session-only -- leaving or reloading the page ends it for good.

Terrain: hills, trees, rocks, and wildflowers are scattered across the meadow for texture; hills also double as the hillside sites wolves den in. A few dense forest clusters and quarries dot the map too, along with scattered felled logs -- all harvestable by the worker for wood and stone.

Clan traits: each restart, the three clans' dens land somewhere different, and whichever clan's den sits farthest from any water learns to fish — a 30% chance per attempt, used only as an emergency lifeline when a wolf is truly at risk of starving, not a routine food source. Whichever clan is most isolated from the other two gets noticeably more stamina before tiring, useful for the extra travel that isolation demands. The remaining clan simply has the fastest legs of the three. If one clan ever grows to dominate the whole wolf population despite the others' traits, some of its adults migrate to whichever clan is smallest, so the three-way dynamic keeps going instead of collapsing into one dominant clan.

Field notes: every wolf has a name and one of five personality traits (Bold, Cautious, Aggressive, Playful, Loyal) that lightly bias its behavior — Bold wolves defend a wider territory, Cautious ones drink and eat before it's urgent, and so on. Rabbits aren't named individually (there are hundreds of them), but each burrow is a named warren you can track as a group. The "Field notes" panel logs births, deaths (with a plain-language reason — dehydration, starvation, predation, old age, a border clash), clan dispersal, and immigration. Pick a wolf, a whole clan, or a warren from the dropdown (or just click one on the map) to also see a running narration of what it's doing moment to moment. Litters being born and new animals arriving from outside the meadow also pop up as a brief on-screen notification, along with rain arriving and clearing.

About that dehydration: the log will show you the real reason case by case — usually either a rabbit that spent the day being chased and never got a clear run at the water, or one that was simply too far from the river or a pond when its thirst caught up with it. It's not that they're forgetting water exists; hunger, fear, and travel time all compete for the same limited time in a day, and occasionally water loses.