Planned Release Date: Nov 10, 2026

About This Game

One fruit fly. A brain model you can watch.

AFEI is a quiet observation game. One fruit fly lives in a glass box on a windowsill. You set up small experiments, then watch what the model and the physics body do.

What you do

• Place fruit. Up to three pieces: strawberry or banana, from fresh to mouldy, close to the fly or far away. Fruit ripens in real time.
  
• Tap the glass. Code sends a synthetic looming signal to the fly's looming-detector neurons; the model's take-off neurons decide whether it takes off; the jump and flight are assisted.
  
• Open the brain map. Show the whole central nervous system, the brain, or the smell path. Fibres are drawn from measured neuron shapes (simplified); the glow is the model's firing at that moment.
  
• Look closely. Orbit, zoom and follow the fly, and give it a name.
  
• Complete 20 tasks. From "Watch it eat" to "Weaker fruit reached first". Each task gives a card with one sentence on what the model does and what the code does. Finish all 20 for a full clear, then keep watching as long as you like.

The science, plainly

Afei's brain is a leaky integrate-and-fire (LIF) model of all 165,122 neurons and about 25.6 million neuron-to-neuron connections in the Male CNS v1.0 connectome, the published wiring map of one male fruit fly's brain and nerve cord. It runs on your PC in 1 ms steps. The body is the NeuroMechFly physics model, running in MuJoCo. The model receives smell, taste, leg contact and, when you tap, a looming signal. It cannot see (the eyes are not wired in yet) and it does not learn. All neurons share one parameter set, and whether a connection excites or inhibits comes from the dataset's machine-learning predictions of each neuron's transmitter. Much of the behaviour is assisted by code, and the game marks each assist. Among them: half of the walking drive, the flight itself, turning toward fruit, extending the proboscis, grooming, the walk/rest rhythm, wall-following, and a stronger smell input when it is hungry. Model time runs slower than real time: about half to nine-tenths of real time on the tested laptop. This is a computational model with simplifications and engineering assists. It is not a recording of a real brain, and it is not a complete fly.

No way to fail

The fly does not die and tasks never expire. The model pauses while the game is closed; fruit keeps ripening in real time. Rewards (keepsakes and scenes) are for you and never change the model.

AI assistance: code, images, text, music and sound effects were made with the help of AI tools and reviewed by the developer. The Japanese text is an AI-assisted translation, not yet checked by a native speaker. The Simplified Chinese text is converted from the Traditional Chinese by a rule-based converter (OpenCC) with a term list drafted with AI assistance, not yet checked by a mainland reader. Afei's brain is a simulation of a connectome, not generative AI.

Features

• A simplified brain model built from the published Male CNS connectome, computed on your PC in 1 ms steps
  
• A physics body with six legs, gravity and contact (NeuroMechFly in MuJoCo)
  
• A cartoon fly; leg shapes from the flybody model
  
• Brain map with simplified neuron fibres, the model's current firing, and readouts: smell input left/right, taste, foot contact, neural drive left/right
  
• Up to 3 fruits, 2 kinds x 4 ripeness stages; with one fruit out, its tag shows the smell-path neurons' current firing rate
  
• 20 tasks (16 easy, 3 harder, 1 very hard), 20 cards and a full clear; keepsakes and two more scenes (a veranda and a night windowsill) as gifts
  
• Every engineering assist marked with an icon and a note; model time shown on the brain map
  
• Original music and sound effects
  
• Traditional Chinese, Simplified Chinese, English and Japanese, switchable in Settings (Simplified Chinese: converted from the Traditional Chinese; Japanese: AI-assisted translation)
  
• Autosave; optional background mode in windowed play

Real data, model and engineering assists

• Real data: neuron shapes and connections from the published Male CNS connectome; transmitter types are the data authors' machine-learning predictions.
  
• Model: Afei's brain is a simplified LIF model; its body runs on NeuroMechFly and MuJoCo physics. On-screen numbers are model output, not recordings. It is not a real brain and not a complete fly.
  
• Engineering assists: the walking rhythm, steering toward fruit, the grooming and rest schedule, and the take-off and flight assists are program code, and the game labels each one.

Data and tools

Neural wiring and neuron shapes: Male CNS v1.0 connectome (FlyEM at HHMI Janelia, University of Cambridge, MRC Laboratory of Molecular Biology, Google Research), CC BY 4.0. Simplified for this game (signed weights for a LIF model, simplified skeletons and region meshes); the data creators do not endorse this game. Body: NeuroMechFly v2 / FlyGym (Apache 2.0) and the MuJoCo physics engine (DeepMind Technologies Limited, Apache 2.0). Leg shape from flybody (TuragaLab, Apache 2.0). Fonts: Noto Sans TC, SC and JP (SIL Open Font License 1.1). Made with Unity.

AI Generated Content Disclosure

The developers describe how their game uses AI Generated Content like this:

Made with AI assistance and reviewed by the developer:
- Code: written with AI coding assistants.
- Visuals: the room, props and interface are built by code written with AI assistance. The app icon and loading portrait are AI-generated: they were made with ChatGPT image generation (OpenAI) from text prompts, using a render of the in-game fly as the character reference and a fruit-fly photo for body proportions; the developer chose the images and did not edit them beyond cropping and resizing. The Steam app and shortcut icons are made from this app icon. Store capsules are in-game renders with Noto Sans TC Bold lettering; no AI image generator was used.
- The fly's head and body are a textured 3D model generated with Tripo AI (image-to-3D) from an AI-generated concept image (ChatGPT image generation, OpenAI) that the developer chose, then reshaped and cleaned up by scripts written with AI assistance to fit the game's physics; its legs, wings, mouthparts and scarf are the game's own (the scarf's shape follows the concept image; the legs are shaped after the open-source flybody model, Apache 2.0, not AI-generated).
- Music and sound: scores and a small synthesiser program written with AI assistance. No AI audio generator and no samples were used.
- Text: Traditional Chinese and English text in the game and on this store page written with AI assistance. The Japanese text is an AI translation, not yet checked by a native speaker; the game says so. Simplified Chinese is converted from the Traditional Chinese by a rule-based converter (OpenCC) with a term list drafted with AI assistance, reviewed by the developer; not yet checked by a mainland reader.

Nothing is generated by AI while you play. The fly is driven by a simulation of 165,122 model neurons wired from real fruit-fly connectome data, a physics body, and program assists that the game labels. Its wiring is fixed and it does not learn. It is not a chatbot or a generative AI.