They threw a digital fly into Doom and Minecraft: it drowned, learned nothing

The basis is a connectome, the complete wiring diagram of a brain. The FlyWire project assembled one for an adult female fruit fly: more than 125,000 neurons and about 50 million connections. Google went further and mapped an adult male's brain and nervous system in full, over 166,000 neurons.

In March 2026 Eon Systems joined such a diagram to a virtual fly body with 87 joints and ran it in a physics engine. The result walks toward food guided by taste cues, stops to groom itself when fictive dust is sprinkled on it, and eats when it arrives. No rewards or reinforcement were used to teach it: the behaviour came out of the wiring itself.

Then the internet got hold of it, and the fly went on a tour of video games.

• Doom. On 3 September engineer Alex Wormuth launched the DOOMFLY project and published the code: every game frame stimulates sensory neurons, brain activity is mapped to button presses, and damage sends a short aversive signal into two dopamine cells, meant to work as punishment and teach the fly something.
• Super Mario 64 and Beat Saber. The same model was wired into both, with no scientific ambition, just because it was possible.
• Minecraft. On 19 August a YouTuber called ro0oney1 connected an open model to the game. The first body was a spider: it wandered off and drowned. The second was a bee: it flew around the map and completely ignored the YouTuber attacking it.
• The virtual fly body. The most serious experiment of the lot, and the only one where the fly lives in a body resembling its own.

This is where the funny part ends. In the Doom experiment the fly played around three thousand runs back to back. Survivability did not improve at all: no basic reflex, no tactics against the monsters. The brain simply fired along its fixed wiring, the same way every time.

That matters more than it looks. Wiring produces recognisable behaviour where the body and senses are real: walking, grooming, feeding. It does not produce the ability to learn from experience if the model lacks everything else a living brain learns with.

The explanation is duller than any mystery. A graphics card's picture looks nothing like what a fly brain expects from its eyes, and a spider's body answers with the wrong signals. There are no hormones, no proper feedback from the limbs, no familiar passage of time.

The brain receives gibberish and replies with chaos. This is not consciousness rebelling inside a block world. It is a creature given someone else's eyes and legs with everything else switched off. The drowned spider is not a tragedy, it is a verdict on the interface.

The honest answer is that nobody knows. But some things are certain, and the company writes them down itself.

The model has no internal state, no plasticity and no learning, no hormones. The neurons are simplified into basic threshold elements. Only a small part of the senses is connected. The authors warn directly that this should not yet be read as proof that wiring alone is enough to recover a full behavioural repertoire.

So if there is anything it is like to be this fly, it is a heavily trimmed fly. And there is nothing to check it with: we cannot measure another creature's experience even in a living fruit fly. You cannot ask it, and behaviour does not settle it, as this fly shows by acting convincingly while learning nothing.

The question everyone actually came for. Let us count on our fingers.

• A fly has around 140,000 neurons, a human roughly 86 billion. That is six hundred thousand times more, and the connections scale up even harder.
• No complete wiring diagram of a human brain exists. The fly one took years of microscope work, and the company's next target is a mouse brain, not a person.
• Even with the diagram in hand the fly came out incomplete and unable to learn. A human without hormones, a body and memory is not a human, it is a very expensive screensaver.
• The main question is not technical: is the copy you, or not you any more? The original does not disappear when copied and carries on with its life.
• The practical question is worse: who owns the copy and whose servers does it run on.

Fact: the digital fly exists, its behaviour was demonstrated, the wiring and the code are published, and the limitations are listed by the authors themselves. The Doom experiment's code is public too, and nobody hid the negative result.

Also a fact, a smaller one: the game experiments were done by enthusiasts for videos, and they never called it a transfer of consciousness.

This part is speculation: that the fly suffers in the block world, that somebody is secretly preparing to digitise people, that a mind has already been uploaded. None of the three has any evidence behind it.

It makes a fine illustration for the wider argument about AI: convincing behaviour outside, emptiness inside, and appearances that cannot be trusted. The fly walks, grooms and eats like the real thing, shoots in Doom as best it can, and after three thousand attempts is not one bit better at it. Before arguing about whether it feels anything, ask what was put into it in the first place.