All models are wrong, some are useful.
breve runs flocks, ant colonies, epidemics, markets and walking creatures from a short script and a small JSON file. Nothing is hard-wired: the rules, the bodies and the numbers are all yours to change while it runs, and to compare side by side.
These are live. Each one starts when you scroll to it and pauses when you scroll away. Drag to look around.
A behavior is a plain function. Edit it and the running simulation picks it up.
Sweep a parameter, fork a run mid-way, or let a search find the settings that work.
Give any agent a rule, a small neural network, a keyboard or a language model.
The assistant turns "make the predators slower" into a checked change you can accept or undo.