Simulated fruit-fly brain with 138,639 neurons is learning Super Mario Bros. 3 live

Inevitable_Emu2722 · reddit · 2026-09-23

A hardcore open-source project simulates the entire FlyWire fruit-fly brain connectome — all 138,639 neurons and 15,091,983 connections, frozen exactly as published in Nature (signs included) — training it live to beat World 1-1 of Super Mario Bros. 3, with the raw training process streamable (not a replay).
Key design:
Vision: full screen → 15×13 grayscale × 4 temporal frames → 10,855 visual-input neurons (ON/OFF pairs).
Annotated circuits provide priors, not cheats: LC4/LPLC2 looming (314 neurons), DNg02 flight/thrust (25), Giant Fiber escape (2), MDN backward (4).
41,692 central+descending neurons read out via a fixed signed hash.
PPO plus self-imitation on agent-discovered trajectories only; every episode starts at the true World 1-1 start.
The live view shows raw NES gameplay, whole-brain activity lighting up, the exact 15×13×4 'retina' behind each decision — and a real photographed housefly foreleg on the NES controller (no real flies harmed).

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