The science
Water and grass set the map. Each of the 32 x 32 grass cells grows toward a target biomass that depends on the season and on distance to water: target = w x (0.45 + 0.5 x patchiness) + (1 - w) x 0.62 x moisture, with w the wetness. In the wet season grass is lush everywhere; in the dry season only cells near the permanent pool stay green, so herds are pulled toward it - the same pressure that drives the real Serengeti-Mara migration.
Needs. Every animal tracks water, energy and (for sprinting) stamina. Water falls at a species rate (zebra and elephant need regular water, giraffes and gazelles can go much longer). Energy falls with a basal rate plus running cost proportional to v^2, and rises by grass x gain while grazing. At zero for long enough an animal dies of thirst or starvation.
Waterhole turns. The shore has a limited number of drinking slots. Animals queue; an elephant (priority 6) can displace a smaller drinker. Drinking happens in bouts: a drinker lifts its head every few seconds, and the bout lengthens with the number of drinkers nearby (the many-eyes effect), shortens and the head-up time grows if a predator is within about 40 m of the water's edge, and thirsty animals (or ones that have waited 30 s) take the risk anyway.
Hunting energetics. A predator cycles rest, patrol, stalk, chase, feed. Top speeds follow the field numbers on the cards, but a chase draws on a stamina budget (cheetah ~7 s of full speed, lion ~12 s, hyena ~22 s) that drains as (v / vmax)^2. Prey flee with vmax x (0.5 + 0.5 x sqrt(stamina)) and zig-zag (gazelles most), which costs a pursuer speed because it must turn. Pride and clan hunters fan out around the target. A pounce can still miss (grip 25-45 %, lower against prey that kick - zebra, giraffe). Success rates are an outcome of these rules, not a dial - compare them with the real figures on the cards.
Detection. A prey animal notices a predator with probability depending on distance, how crouched the predator is, whether the prey has its head down, and how many herd mates are already alert. Drinking animals with head down are least likely to notice.
What is simplified. No wind or scent, no calves following mothers, no territories or pride politics, no crocodiles. Hyena scavenging and lion-hyena conflict are left out. Births are modelled as recruitment tied to the herd's body condition. Terrain, trees and grass are decorative: animals cannot be blocked by them except for trunks and shorelines. Models are procedural Blender builds, not scans.