Each island holds one wildlife population, rendered as a swarm of individuals inside a habitat dome. Every simulated year the population grows logistically toward its carrying capacity, then loses individuals to habitat loss and poaching, discounted by however much of its range sits inside a protected area (IUCN IUCN Protected Area categories I–VI: strict reserves through managed-resource areas, all off-limits or restricted to the same threats here).
dN/dt = r·N·(1 − N/K) − threat·N
threat = (habitatLoss·sensH + poaching·sensP) · (1 − 0.9·protection)
Every few simulated years the population's size is checked against a rolling memory of itself (a proxy for the Red List's "three generations" decline window) and assigned the closest matching category, using simplified real IUCN criteria on population size and decline rate:
- LC — Least Concern: stable, no major decline.
- NT — Near Threatened: mild decline or small range, close to qualifying.
- VU — Vulnerable: population below ~1,000 or ≥30% decline.
- EN — Endangered: population below ~250 or ≥50% decline.
- CR — Critically Endangered: population below ~50 or ≥80% decline.
- EW / EX — Extinct in the Wild / Extinct: population has hit zero.
Species differ in growth rate, carrying capacity and sensitivity to each pressure — a slow-breeding megafauna species with high poaching sensitivity collapses under pressures that a fast-breeding generalist shrugs off, mirroring why a single global policy affects real species so unevenly.