Flypet

This pet actually has a brain.

Inside is the wiring of a real male fly: 165,122 neurons and their connections, simulated on your phone while you watch. When it bolts, eats or grooms, that brain makes the call.

So what will it do next? You'll have to see.

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Connectome data: MaleCNS v1.0, Janelia Research Campus (FlyEM) and collaborators, CC BY 4.0. Janelia is not involved with and does not endorse this app.

◢ 01//ITS BRAIN

Crack open its head

◢ How it works

The wiring is real. Then it decides.

It was mapped with an electron microscope. Your phone switches it on, with a simple model for each neuron. And depending on which ones fire, it flees, eats, grooms or sets off walking. What can't be read from a connectome yet, like the body or the hormones behind hunger and sleep, we simulate separately using studies published up to 2026, as faithfully as we know how. The diagram shows the split.

Connectome data: MaleCNS v1.0, Janelia Research Campus (FlyEM) and collaborators, CC BY 4.0. Janelia is not involved with and does not endorse this app.

Diagram in three steps: real wiring, with 165,122 neurons from a male fly; your phone switches it on, with a simple model of each neuron; then it decides. Below, two lists. Its brain decides: fleeing, extending its proboscis, grooming, and walking if its brain says so. Simulated separately: senses, body and gait; hunger, sleep and digestion; finding food by smell; setting off for no reason. Below, why: A connectome maps the connections between neurons, but not the body or the hormones behind hunger and sleep. Those can't be read from it yet, so we simulate them using studies published up to 2026, as faithfully as we know how. Smell-tracking is a published algorithm, and setting off for no reason is a nudge from the app.

◢ Why

Spook it. Then ask it why.

Give it a quick tap and it'll usually take off. Tap "Why?" and it shows you what it saw and which neurons fired, names and all.

The fly up close with the "Why did it escape?" sheet on top: it saw something big coming at it very fast, through visual neurons LC4 and LPLC2; its takeoff neurons switched on, the giant fiber DNp01; and it jumped and flew off.

◢ Its brain, live

Watch it light up.

165,122 neurons, and every spark is one firing right now. Turn it with one finger, pinch to zoom, and tap any of its 156 named groups to see what it does.

Its nervous system in 3D on a black background: 165,122 neurons, with the ones firing lit up in gold, and below it the list of 156 named groups of neurons.

◢ The lab

Switch off a neuron. See what happens.

Turn neurons on and off, guess what it'll do, and compare with what's been published about real flies. It usually matches. If it doesn't this time, it tells you.

Two lab screens: the list of experiments (walking backwards, walking, turning, sweet taste, without MN9 and more) and the result of "Without MN9": neither real flies nor yours put out the proboscis.

◢ Anatomy

Find the neurons that make it reverse.

The real shape of its neurons in 3D, layer by layer, from the same scan. The green ones are MDNs: switch them on in the lab and it walks backward.

Two 3D views of its nervous system: the translucent brain dotted with gold points and, below it, the MDN neurons in green, running between the brain and the nerve cord.

◢ 02//ITS LIFE

It only gets one

◢ Day to day

Have you fed it today?

It gets hungry, it gets sleepy, and it sleeps at night on your phone's clock. Put out some grape, banana, apple or strawberry and watch it climb up to eat. Fruit ripens and rots, and whatever it leaves behind is yours to sweep up. Time keeps going when the app is closed, and when you come back it tells you what you missed.

Two screens of its room: by day, the fly eating, with its hunger and sleep on the card at the top; and at night, the same room in the dark with the fly asleep.

◢ Its life

How far will yours make it?

It lives about two months, in real time. Fewer if it goes more than two days without food. When it's gone, you say goodbye, it stays in your history, and a new one hatches.

The fly on its back with the card "Its life has come to an end": it lived 47 days and died of old age. Beside it, the fly history: the three before it, how long each one lived, and the fourth, just hatched.

◢ 03//YOUR MOVE

Make it yours

◢ Its room

Build its room. Then step inside.

A bed, a desk, a die, a geode, all at its scale, plus lights to switch on. Change the floor and walls. Then open the lock and walk around the room with the joystick, right next to it.

Walking with the joystick around a room with a desk and computer, a bed, a side table and a clay floor. Beside it, the Decoration panel, with a die, marble, stone, flower, mini bed, mini table and more objects.

◢ Flycoins

Look after it. It pays off.

You earn Flycoins by feeding it when it's hungry, cleaning up, coming back each day and collecting what's noted in the book. You spend them on looks, decorations and gadgets. If you'd rather, you can also buy them.

How to earn Flycoins: cleaning up with the Broom, +1; feeding it when it's hungry, +2, once every 30 minutes; coming back every day, +5 plus 1 more for each day in a row, up to 7 days. Below, 6 of 15 achievements with Flycoins to collect and three things worth saving for: the Golden fly, a little house and a food dispenser.

◢ Looks

Change its look.

The Golden fly up close, all polished gold with red eyes, on the edge of an amethyst geode. — The Golden fly doesn't come cheap.

The Collector fly, turquoise with rainbow iridescent eyes and a sash of medals, by an amethyst geode. — The Collector can't be bought.

The Porcelain fly, white with blue patterns, eating on top of a cut strawberry much bigger than it is. — The Porcelain fly, busy with a strawberry.

The Anime fly, cartoon-style with big eyes, in front of a green sofa in a room with pink walls. — The Anime fly, in a living room you can decorate.

Change how it looks and it's still the same fly: its looks don't touch the simulation.

◢ Flydex

Don't let a single fly get away.

The Flydex has 11 flies: Golden, Neon, Robot, Anime and more. Some cost Flycoins and some you have to really earn: the Legend needs every achievement, the Scientist the whole lab, and the Specter three flies that reach old age with you. Get all 11 and the Collector is yours, a reward you can't buy.

The Flydex in the book and, next to it, the reward looks: 7 of 11 flies, each with its look and what it takes (the Specter, 3 lives; the Scientist, the lab; the Legend, achievements) and, at the bottom, the Collector in shadow, the reward for completing it.

◢ 04//NO TRICKS

What this is and isn't

The wiring is real. The model of each neuron is a simplification (integrate-and-fire), the kind used in research. Its senses, body, hunger and sleep are simulated separately from published studies, because they can't be read from a connectome yet.

Finding food by smell is a published algorithm and doesn't come from the connectome, and when it sets off for no reason, the app gave it a nudge: without one it would just stand there.

It isn't a real fly. It's the closest we've managed.

Connectome data: MaleCNS v1.0, Janelia Research Campus (FlyEM) and collaborators, CC BY 4.0. Janelia is not involved with and does not endorse this app.

The screens are from the game. The save data you can see in them (days, coins, history, collection) is sample data.

◢ 05//WHERE

What will it do next?

Where to get it

It's currently in closed testing on Google Play. If you have Android, you can try it now and help me publish it. Open it 7 days in a row before launch and you'll get a fly and a plaque no one else will ever have.

Become a tester→

Who makes it

Flypet is created by Jorge Graells. The fly's brain is the real MaleCNS connectome (Janelia, CC BY).

Privacy and contact

Flypet privacy policy · Terms of use

Contact: dev.graells@gmail.com

What it costs

Free, with no ads. Optional purchases: Flypet PRO (one payment, no subscription), the Founder pack, for anyone who wants to support the project, and Flycoin packs, the in-game currency, which you also earn by playing. The commemorative 2026 founder plaque is a gift for anyone who plays in the first six months after launch, with nothing to buy.