DesktopFly puts a live fruit fly brain on your macOS desktop

This virtual 3D fruit fly lives on your macOS desktop and runs on a live spiking simulation of a real fly's connectome.

Developer Denis Sergeevitch built DesktopFly, an open-source macOS app where an insect wanders across your windows and reacts to your actions. Instead of using scripted behavior, it runs a 668-neuron circuit with ~19,000 real synaptic connections sourced from the FlyWire neural dataset. When you flick your cursor toward it, looming-detector neurons process the movement and fire escape command neurons in about 4 milliseconds.

Why it matters: It turns complex neurobiology into an interactive desktop pet. The fly doesn't rely on basic IF/THEN statements to walk, sleep, or turn—its actions happen because real simulated neurons fired through physical synaptic wiring.

Try it / know this: You can build the app on macOS 13+ with Xcode Command Line Tools, and it requires zero system permissions. Toggling the brain window shows 23,210 rendered neuron positions that you can click to trigger specific behaviors, like grooming or steering. It even reads your Mac's thermal state—a hotter CPU makes the fly move faster.

Tamagotchis relied on basic timers; desktop pets now run on 19,000 simulated synapses.