A simulated fruit-fly brain (FlyWire connectome) plays Game Boy games on a 24/7 stream.
Find a file
acamilo 3cf706c96a rewards: read the conversation's argument once the cartridge has written it, and a ROM test
The first cartridge run found what the synthetic trace could not. In the
Viridian Forest north gate the font bit rose on one frame and DisplayTextID's
argument reached wSpriteIndex twenty frames later: DisplayTextIDInit loads the
font's tiles into VRAM first. Until then the byte still names the previous
text's subject, which may be the person in front of the fly from a conversation
that did not pay. So the watch now remembers the byte from the last ready
frame and reads it once, when it changes or after 45 samples, and only while
the bottom dialogue box is drawn (the start menu draws its own elsewhere); a
box that closes first is read on the closing sample if the dialogue box was up.

tests/rom_engage.rs, gated on FLY_ROM and FLY_ENGAGE_CHECKPOINT: from the rung-10
Pewter checkpoint, with the checkpoint's own v6 ledger restored (the migration,
on real game state), a scripted walker goes down Route 2 into the forest's north
gate, talks to the old man three times (one payout, 0.10) and picks up the
Antidote ball at (25, 11) (one payout, 0.15, "FOUND ITEM #11"); pressing A at
the empty tile pays nothing, and after rolling the emulator back to before the
pickup, taking it again pays nothing. No boundary payout lands while an indoor
header is loaded.

It also measured the warp transition: for about thirty frames of
PlayMapChangeSound wCurMap already names the destination while the tileset and
warp table are still the map being left, so the exit the fly stands on is
classified by the map it belongs to -- a town door still pays its on-exit half,
keyed under the building's id as before, and a building's door does not. A unit
test pins both directions.
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.forgejo/workflows flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
.github/workflows flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
apps/stage stage: the explore row reads "new find" 2026-09-23 14:34:10 +00:00
data/fafb-v783 flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
docs docs: v0.5.5 status 2026-09-23 13:43:21 +00:00
infra Merge fix/loop-row58: the gym's people are there when the screen does not draw them, and the game's own moves write no ledger 2026-09-23 13:43:18 +00:00
packages session types: shared decoderConfigDigest vectors from both decoder presets 2026-09-23 09:00:12 +00:00
services rewards: read the conversation's argument once the cartridge has written it, and a ROM test 2026-09-23 14:34:10 +00:00
tools flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
.gitignore flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
CLAUDE.md flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
CONTRIBUTING.md flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
LICENSE flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
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Makefile flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
NOTICE flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
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README.md flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
ROM-POLICY.md flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00

flybrain

A simulated fruit-fly brain that plays video games. A connectome-constrained spiking network reads the screen, its population rates become controller inputs, and a scalar reward nudges a bounded set of Kenyon-cell to MBON gains.

The library is @flybrain/brain in packages/brain. It holds the connectome dataset format, the LIF kernel, the plasticity rule, the population-rate readout and the activity-map geometry. It holds no game, no emulator and no reward rules: those belong to whatever embeds it.

Workspace layout

Path Contents
packages/brain the library (@flybrain/brain)
data/fafb-v783 FlyWire-derived browser artifacts (CC BY-NC 4.0)
tools/ the Python builder that regenerates data/ from official Codex exports
docs/ overview, dataset format, model, plasticity, readout, integration, limitations, verification
services/flysim the Rust service: brain, emulator, snapshot feed, control API, checkpoints
apps/ planned: one directory per game demo
infra/ planned: deployment for the 24/7 stream (see docs/streaming-plan.md)

Quick start

npm ci
npm test
npm run typecheck

76 tests, about 7 seconds. There is no build step. npx tsx packages/brain/examples/node-random-frames.ts 60 runs the full 139,255-neuron brain with the Game Boy readout on noise frames in plain Node (about 0.9x Game Boy real time single-threaded on a WSL laptop).

Usage

import { NeuralAgent, gameboyDecoderConfig, toButtonMask } from '@flybrain/brain';
import { loadBrainDatasetFromDir } from '@flybrain/brain/node';

const dataset = await loadBrainDatasetFromDir('data/fafb-v783');
const agent = new NeuralAgent(dataset, { decoder: gameboyDecoderConfig() });
agent.warmup(firstFrame);                        // 2,500 ms with plasticity off, then calibrate

// every emulator frame:
const { active } = agent.tick(framebuffer, {     // RGBA 160x144 by default; any size via config
  rewards: [{ value: 0.5 }],                     // scalar rewards your game adapter detected
  boot: !inGame,                                 // relaxes Start/Select throttling on title screens
});
emulator.setButtons(toButtonMask(active));

const checkpoint = agent.exportState();          // bit-exact resume, validated on import

The lower layers (LifNetwork, RewardModulatedStdp, PopulationDecoder) are exported too for hosts that want to run the loop themselves.

integration.md has the full per-frame loop, the fractional frame timing and the checkpoint contract.

Documentation

  • Overview: the pipeline, the layer map and the design principles.
  • Dataset format: artifacts, CSR layout, weight encoding, every role and its count, fingerprinting, regeneration, license.
  • Model: the 1-ms LIF kernel step by step, every default constant, the retina projection, the RNG, state export and version strings.
  • Plasticity: edge selection, the eligibility and reinforcement equations, statistics, topology hash and the explicit non-claims.
  • Readout: scores, exclusive groups, pulse channels, the blocked-direction cooldown, the Game Boy preset table and checkpoint versions.
  • Integration: what a game must provide, the Pokemon Red integration as a worked example, and a sketch of a platformer adapter.
  • Limitations: what is not claimed, what is unproven, measured throughput.
  • Verification: the oracle-test strategy and what each test file covers.
  • Streaming plan: headless capture, Twitch, VM design and the phased plan for a 24/7 stream.
  • Artifact builder: how to regenerate and verify data/fafb-v783.
  • Data attribution: source, license and citations.

Provenance

The network, plasticity rule, readout, FlyWire pipeline and activity viewer were extracted from the fly-plays-pokemon prototype so several game demos can share one core. The default configuration reproduces that prototype's kernel bit for bit, and verbatim copies of its modules live in packages/brain/tests/legacy/ as oracles. Built with Astra.

Licensing

The data/fafb-v783 artifacts are derived from the FlyWire FAFB public Codex v783 exports and are licensed CC BY-NC 4.0. That is a non-commercial license, so a commercial demo needs a different data source or separate permission. Citations and the list of modifications are in data/fafb-v783/ATTRIBUTION.md.

No license has been chosen for the code in this repository yet.

ROMs and save states never enter this repository.