The Internet Is Torturing a Fruit Fly, but HOW??

Google and Janelia open-sourced a complete fly brain wiring diagram, the male CNS connectome: 166,691 neurons and ~125 million connections across brain and nerve cord. The internet immediately put it in Doom, Minecraft and Beat Saber, and gave it $100 to trade Bitcoin. This is the fly brain explained like a foundation model: the architecture, the real numbers, the honest limits, and the full how-to, browse it, query it, simulate it, embody it, and read the open-source Doom demo. What's inside The map behind the games: MaleCNS v1.0 — 166,691 neurons, ~125 million connections, brain plus nerve cord. The map behind the science: FlyWire's adult female brain, brain only — 139,255 neurons, ~50 million chemical synapses, 7,000 slices at 40 nm, 33 person-years of proofreading. The architecture: most neurons sit in the optic lobes, 51 antennal glomeruli fan into ~2,600 Kenyon cells per hemisphere, a central-complex ring holds the heading compass, and ~1,300 descending neurons carry commands out. The honest limits: wiring is not weights — no synaptic strengths, gap junctions, glia or neuromodulators — and the Doom/Minecraft/Beat Saber demos are open-source community projects, not peer-reviewed research. The ladder: browse all 139,255 neurons free in FlyWire Codex → pull them with one CAVEclient query → activate and silence neurons in a whole-brain simulation on a consumer GPU → drive an 87-joint FlyGym body → read the Doomfly source. What you can do this weekend: the whole download-and-poke path is free, no lab required. Read as an architecture, the fly brain is oddly familiar — stacked sensory layers, a sparse hash-table memory in the mushroom body, a ring-attractor compass in the central complex. And the structure alone carries real computation: the 2024 Nature whole-brain model reproduced optogenetic results at over 90% agreement using one free parameter. The simulated fly still loses at Doom thousands of times — that's the interesting part. Timestamps 0:00 A fly brain plays Doom 0:27 FlyWire connectome: the female brain map 0:59 MaleCNS: the map that ran the demos 1:22 Inside the fly brain: optic lobes, mushroom body, compass 3:22 Wiring is not weights: the honest limits 4:26 How to run a connectome: three levels 4:46 Level 1 — FlyWire Codex in your browser 5:13 Level 2 — Python queries with CAVEclient 5:48 Level 3 — whole-brain simulation on a GPU 6:24 Doomfly: the open-source Doom demo 6:45 What it costs: the 100 TB wall 7:37 What you can do this weekend Sources ↳ FlyWire Codex — browse all 139,255 neurons free: https://codex.flywire.ai ↳ FlyWire connectome paper (Nature, Oct 2024): https://www.nature.com/articles/s41586-024... ↳ Whole-brain LIF model, Shiu et al. (Nature, Oct 2024): https://www.nature.com/articles/s41586-024... ↳ MaleCNS v1.0, Janelia (2026): https://male-cns.janelia.org/ ↳ MaleCNS release, Google Research: https://blog.google/innovation-and-ai/tech... ↳ Doomfly source code (open source): https://github.com/nftechie/doomfly ↳ Eon Systems embodied fly (March 2026): https://eon.systems/updates/embodied-brain... ↳ Eon's whole-brain simulation repo: https://github.com/eonsystemspbc/fly-brain ↳ FlyGym / NeuroMechFly v2 body: https://neuromechfly.org ↳ CAVEclient — Python access to FlyWire: https://caveconnectome.github.io/CAVEclient/ Credits & disclaimer The Doom, Minecraft and Beat Saber demos are open-source community projects — fan and engineer builds, not peer-reviewed research. This channel is not affiliated with FlyWire, Janelia, Google Research, or the teams behind these datasets. Dataset credits: the FlyWire Consortium (adult female brain, 139,255 neurons, Oct 2024) and the Janelia MaleCNS team with Google Research (adult male CNS, 166,691 neurons, 2026).