A mapped fruit fly brain is now playing Doom
Google and HHMI Janelia mapped the nervous system of a male fruit fly. A developer then wired the map to Doom.
The map
On September 3, Google Research and the Howard Hughes Medical Institute's Janelia Research Campus announced a complete map of the brain and central nervous system of an adult male fruit fly. The dataset, MaleCNS v1.0, contains more than 166,000 neurons and 125 million synaptic connections, making it the largest brain map by neuron count to date.
The team cut the nervous system into millions of thin sections, imaged each one with an electron microscope and used AI to build 3D neuron models from the 2D images. Scientists then checked and annotated the results. A wiring map like this is called a connectome.
Where did Doom come in?
A few days after the release, software engineer Alex Wormuth shared a project called DOOMFLY. Each frame of the game stimulates sensory neurons in the simulated brain, and neural activity is mapped to game controls. When the character takes damage, a stimulus goes to two dopamine cells (PPL101), which the system uses as a learning signal. The project was livestreamed online.
Results are modest so far: at the time of reporting, the simulated fly had tried the game more than 6,000 times without finishing it once.
Mario, Minecraft and more
With the map open to everyone, others joined in. Developer Jessica Paquette connected the simulated fly to Super Mario 64; Mario jumps and bumps into walls. Paquette said all of the code was written with GPT-6 Astra. Another user ran all 166,700 neurons inside Minecraft, and Beat Saber experiments were shared too.
What does it mean?
These projects do not show that a fly has learned to play games. A connectome is like a wiring diagram: it shows how neurons connect, but on its own it does not tell you how and how strongly those connections work in a living brain. The game experiments mostly show how quickly and creatively open scientific data can be put to use.
The real scientific goal is to understand how nervous systems perceive the world, respond to stimuli and how damaged neural pathways might one day be repaired. Google notes that mapping the roughly 86 billion neurons of a human brain in the same detail is not yet possible.