A virtual pet fruit fly with a real Drosophila brain.
You feed it, put its lights on and off, and watch it sleep. What makes it more than a Tamagotchi is that its hunger and sleep run on actual fly biology, and the circuits driving that behaviour are real neuron populations from Virtual Fly Brain — which the game can re-query live while it runs.
Grab PetFly-win-Setup.exe from the
latest release. It installs per-user with no admin
prompt and updates itself from then on. PetFly-win-Portable.zip is the same
game with no installer.
| Key | Action |
|---|---|
1–5 |
offer food (banana, sucrose, yeast, water, quinine) |
L |
toggle lights |
R |
rouse a sleeping fly |
B |
brain panel |
M |
swap fly model |
C / H |
credits / help |
| drag, wheel | orbit and zoom |
Sleep is not a countdown timer. It uses the two-process model that real fly sleep research uses:
- Process C — circadian drive from the pacemaker (clock) neurons. Drosophila is crepuscular: active at dawn and dusk, a midday siesta, then consolidated night sleep.
- Process S — sleep pressure, gated by the dorsal fan-shaped body neurons. It builds while awake and discharges during sleep.
Simulated over three fly days, that reproduces a published fly sleep profile — about 9.3 hours per fly day, with the siesta peaking at ZT7. Starving the pet drops it to 2.2 hours, because hungry flies stay awake to forage. So feed it.
One real second is one fly minute, so a fly day passes in 24 real minutes. The pet keeps living while the game is closed, up to 16 fly hours.
Summer Engine (Godot 4.7), packaged with
Velopack. Brain data harvested from Virtual Fly Brain
through the vfb_connect API.
pwsh tools\build.ps1Exports the project and packages the installer, portable zip and update feed
into dist\. Needs Summer Engine and dotnet tool install -g vpk.
Headless tests:
$s = "$env:LOCALAPPDATA\SummerEngine\current\Summer.exe"
& $s --headless --path . --script res://tests/sim_test.gddocs/DESIGN.md covers the architecture, the animation state machine, the grass shader, and how the VFB integration works.
Code is MIT. Bundled assets keep their own licences — the fly models are CC0 and CC-BY 3.0, the UI is Kenney's CC0 pack, and the brain data comes from Virtual Fly Brain. See CREDITS.md.