In 2021, the internet was briefly abuzz with a very peculiar headline: rats had been trained to play Doom. More specifically, the mice were trained to play Doom II. Four years later, the project returns to the headlines with a substantial update.
Now in the experiment, an additional trigger mechanism allows mice, which interact with the game via new immersive AMOLED screens, to shoot.
It seems that Doom enthusiasts are not only curious to run the game on the most diverse platforms imaginable (like in a Word document), but to allow as many “players” to enjoy the experience.
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Sistema Original
The project, led by neuroengineer Viktor Tóth, has evolved into a second-generation configuration that significantly expands the possibilities of mice within Doom’s graphics engine. The original version already used an intelligent configuration, but it was limited.
In it, the rats were strapped into a harness on a rotating ball, with their forward movement mapped to movement through a simplified Doom II corridor. Rewards came in the form of sweetened water dispensed when the rat performed the desired action.
It was functional, but that was it. There was no real interaction with the game mechanics, so calling it “playing Doom” was a stretch.
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The updated system even maps the real movement of mice in a virtual Doom environment, but now supports more complex navigation and additional inputs. The visual system has been enhanced with a curved AMOLED screen that wraps around the mouse’s field of vision.
This provides a much more immersive and consistent visual environment than previous flat screens.
To provide spatial feedback to animals, the system uses gentle jets of air directed at the mouse’s nose to indicate collisions with walls. This is a non-invasive way to tell the mouse “you bumped into something” without relying solely on trial and error.
More importantly, the system now allows mice to shoot.
A physical trigger mechanism allows animals to activate Doom’s fire command, meaning they are no longer just moving around the gamebut interacting in a way that directly corresponds to classic FPS controls.
It’s still far from tactical combat against demons, but, mechanically speaking, rats now perform multiple distinct actions in the game. However, it is also important to remember that this is not Doom Eternal, so the experience is much simpler.
Privacy respected
The experiment does not involve invasive neural interfaces. The entire system is based on external sensors, movement tracking and reward-based learning. The rats’ physical movements are translated into standard Doom commands, and correct behaviors are reinforced by the reward system.
From a hardware point of view, it is an open source, user-friendly setup rather than a closed, custom laboratory instrument.
This distinction is important because this project was never intended to prove that rats understand Doom in any human sense. The update does not mean that Rodents understand level design, enemy behavior, or objectives.
What the results demonstrate is that the technical platform has matured enough to support richer interactions.
Rats can now perform multiple distinct actions in the game, and the system can reliably evaluate and reward these actions. In other words, the limiting factor is no longer the hardware or the software. Now the limiting factor is training time and experimental planning.
Teaching an animal to associate specific physical behaviors with abstract outcomes within a virtual space is a slow process, and scaling this training requires patience. The updated system paves the way for more ambitious experiments than the original version supported.
Future
The mice aren’t yet speedrunning E1M1, Doom’s first level, but the project has clearly evolved. The update demonstrates real technical progress and indicates the possibility of future experiments that could use game engines as standardized, low-cost virtual platforms.
Doom, once again, refuses to die, and indeed, the Doom engine is doing some heavy, silent work. Its lightness, ease of modification, and decades of history running on virtually anything make it an ideal virtual environment for this type of work.
What seems like a joke at first glance is actually a practical choice: Doom offers a controllable and well-understood 3D world that can be adapted to experimental needs without the need to reinvent a game engine from scratch.
From a scientific perspective, the appeal lies less in the rats slaughtering demons and more in what it reveals about accessible experimental platforms.. It’s about consumer hardware, free software, and a lot of clever engineering being used to explore how animals interact with virtual environments.
This same approach should be familiar to PC hardware enthusiasts: taking existing tools, pushing them to absurd extremes, and occasionally stumbling upon something genuinely valuable.
Finally, it is also an experiment that can be used to create more immersive interfaces for players.
Fonte: Rats Play DOOM.
Source: https://www.adrenaline.com.br/variedades/experimento-bizarro-evolui-ratos-jogam-doom-com-mira-e-disparos-em-ambiente-virtual-imersivo/
