FLYBOX runs a real fruit-fly connectome — MaleCNS, 166,700 neurons and about 25 million synaptic edges, reconstructed from electron-microscope imaging — inside a disposable interactive world. Drop in food, predators, obstacles, or light, then stimulate or silence specific neural populations, lesion connections, or fork the simulation’s state, and watch both the fly’s behavior and its live neural firing change together. Open source, no accounts, and each browser tab gets its own sandbox that vanishes when you close it.